0951: "Working"

[japhmi]

That's why I just get gas at the local warehouse store. It's within a few cents of the cheapest in town, if not the cheapest (according to gasbuddy.com), and I'm there shopping anyway.

However, I almost never wait all the way until my tank is down to a quarter left. I fill up at half tanks, so that I'm not stuck near empty in case of emergency.

[MrRubix]

If you are really concerned about pinching pennies, go into investment banking and earn seven figures before you're 30. Of course, you'd have to survive the first few years where you're earning $100k+ but working 100-hour weeks, effectively selling your soul during your 20's.

Unless you were lucky enough to be born into a rich family, you're going to have to deal with tradeoffs. The hard part is finding the sweet spot. We don't want to work our lives away and forgo too much pleasure in leisure, and yet we don't want to be lazy douchebags who don't earn enough to make ends meet.

This is why it's so important to do what you love -- you'll never work a day in your life. Love your job, and earn enough money to cover expenses and enjoy things in your free time. People like to make it a lot more complicated than it really is. At that point, penny-pinching is just not necessary.

So when IS penny-pinching a good idea? In my opinion, almost never.

The national average commute time was something like 26 minutes (or around 16 miles) one-way last I checked. So if an average car has a 16 gallon tank and gets 25 miles per gallon, that means if we want to fill up every time we hit 25% of our tank capacity, we have 12 gallons which will get us 300 miles, or about 9-10 days worth of commuting before needing to spend ~$3.70+ per gallon, or maybe ~$45 per fill, or ~$135 per month. I could go 10 minutes out of my way to save 10 cents per gallon, which amounts to taking half an hour out of my month to save maybe $4 worth or so.

Just ask yourself, at that point: Can you think of any better way to spend half an hour each month that you'd be willing to pay at least $4 for?

It's not just about giving up time you'd otherwise spend working. It's giving up time you could be putting towards something more worthwhile than the money you save.

[jpk]

And if you drive to the gym, you're paying money to drive to a place where you pay money to ride on a pretend bicycle.

Where i won't fall off the bike or be hit by a car or have inhale fumes from cars and can go for a swim right after in the middle winter.

"inhale fumes from cars" - So what you're saying is, "I drive instead of riding a bike because there's too many cars on the road" ... okay, I can buy that, but it still makes no sense.
"can go for a swim right after in the middle winter". This kinda makes sense. You want to swim, okay. So if you're paying for a pool, could you not get a more efficient use of your time by riding to the gym, going for a swim, and then riding home? (s/swim/your_favorite_gym_activy/) Really, getting your daily exercise as part of your actual life seems much more efficient. It takes me half an hour to ride to work or back, just about exactly what it would take me to take the T and probably about the same as driving. (I don't know anybody stupid enough to drive from my neighborhood to where I work, but google says yes, about the same). This means I'm getting an hour of working out every day, just by doing what I do, without spending any extra time to do it, and its free. If I want to add to that, it's easy: just add a gym membership, paid for with the money I've saved in operating a car or paying for a monthly transit pass.

(This one worries me: "fall off the bike" - does this happen often? Maybe you should see a neurologist. )

[webgiant]

Don't forget about the inevitable wait at the other gas station as there will probably be a ridiculous line if it's 10 cents a gallon cheaper, mostly because people don't understand this.

Drives me up the freaking wall when people don't understand this.

My favorite is when I'm in someone's car and they spend half an hour driving around and around looking for a place to park to save ten minutes walking.

Don't compare apples to pianos. Driving around for half an hour to avoid a ten minute walk isn't the same topic as the comic, since the attempted savings isn't time, it's saving personal energy expended by walking. It's shifting costs from personal energy to personal time, to achieve a substantial savings of personal energy.

People seem to forget that every kind of attempted savings is just shifting the costs somewhere else. The Extreme Couponners who use so many coupons (after finding a store which applies overages against the cost of the non-free items) that they get $1,000+ worth of groceries for "free" are just shifting their money costs of food into the cost of maintaining a huge storage space in their home, the cost of having to do all their shopping in one go, the cost of spending several hours a week just looking for and clipping coupons, and the strange looks from their friends and neighbors watching them scurry around looking for coupons.

People who drive an extra five minutes for a ten cent reduction in gas prices are losing more money than they save, but this may merely be their cost-shifting for an improvement in their own state of mind. Like the Extreme Couponners whose antics probably cost them more overall than any amount they save, the good feeling of apparent thriftiness might be the actual goal, rather than an actual savings of money.

Strictly speaking, on a purely monetary basis giving to charity means you're working for nothing, because you are handing out money for nothing of any material value in return. All you get in return is a good feeling, which, being priceless, makes it financially worthless.

[NiteClerk]

I use about 20 gallons (U.S.) per week in my truck. Suppose my local gas station is 5 cents higher than someone else. That cost me $1 per week, or $52 per year. Big deal. The owner of my local station gave $50,000 to my kids school during a fund drive once. Plus the family that owns it keeps it clean and well lit. I can afford an extra $1 per week to support that attitude.

[webgiant]

And if you drive to the gym, you're paying money to drive to a place where you pay money to ride on a pretend bicycle.

Where i won't fall off the bike or be hit by a car or have inhale fumes from cars and can go for a swim right after in the middle winter.

"inhale fumes from cars" - So what you're saying is, "I drive instead of riding a bike because there's too many cars on the road" ... okay, I can buy that, but it still makes no sense.
"can go for a swim right after in the middle winter". This kinda makes sense. You want to swim, okay. So if you're paying for a pool, could you not get a more efficient use of your time by riding to the gym, going for a swim, and then riding home? (s/swim/your_favorite_gym_activy/) Really, getting your daily exercise as part of your actual life seems much more efficient. It takes me half an hour to ride to work or back, just about exactly what it would take me to take the T and probably about the same as driving. (I don't know anybody stupid enough to drive from my neighborhood to where I work, but google says yes, about the same). This means I'm getting an hour of working out every day, just by doing what I do, without spending any extra time to do it, and its free. If I want to add to that, it's easy: just add a gym membership, paid for with the money I've saved in operating a car or paying for a monthly transit pass.

Swimming is hard exercise, when done right: "Low impact" should not mean "easy." If there's time for a swim but not for a bicycle ride then a car makes sense, especially if there's no time to rest much after the swim.

Of course, I forgo the gym membership entirely by doing most of my grocery shopping and travel needs on a bicycle (and once I'm done building the new bike trailer, all of them). So I entirely avoid the need to drive to take a swim.

(This one worries me: "fall off the bike" - does this happen often? Maybe you should see a neurologist. )

There are valid reasons not to bicycle. Pouring down rain, icy streets, these things make you fall off your bicycle. Speaking with the Voice of Actual Experience, and one time the Voice of Nine Stitches On One's Chin. Sometimes a mechanical breakdown hurls you from your bicycle, in much the same way as a poorly maintained car sometimes injures you. No need for neurological problems to fall off a bicycle, unless road conditions are good and your bike is well-maintained.

If there are too many cars on one route, I pick another one. People who know nothing about bicycles--such as the fact that bicycles are road vehicles and do not belong on sidewalks--need to be ignored as they drive by screaming "Get on the sidewalk [and commit a crime doing so]!" If they're too difficult to pedal, get a recumbent bicycle as soon as you can afford one, as the physics of recumbent bicycles are much easier on the rider.

[JudeMorrigan]

Ok so it's 10 centers per gallon cheaper 5 minutes away. 5 minutes by car probably tranlates to about 1km in a city, which is done at quite low fuel efficiency because of all the traffic lights. Let's say 1:10. So we spend 0.1 liters going there and another 0.1 liters going back. That's 0.05 gallons. Gas seems to cost about 4 dollars a gallon. So the trips costs us 20 cents. We save 10 cents a gallon. An average tank is what, 60 liters, that's 25 gallons. Assuming it's mostly empty we put in 20 gallons, so we save €1.80. For 10 minutes of work. That's €10.80 per hour.

Not a very good wage, but certainly above minimum wage. And it's tax free, extra money above your normal income. So that's actually pretty good. Well worth it.

You did your liter to gallon conversion incorrectly. 60L is about 15.85 U.S. gallons. Also, locally at least, if it took me 5 minutes to go a single kilometer, I'd either assume there was an accident somewhere up ahead or be cursing the terrible luck I was having with the traffic lights.

That said, my back-of-the-envelope calculations are also coming up with a number that's above the minimum wage, but it's considerably closer than the one you wound up with.

[jpk]

My favorite is when I'm in someone's car and they spend half an hour driving around and around looking for a place to park to save ten minutes walking.

Don't compare apples to pianos. Driving around for half an hour to avoid a ten minute walk isn't the same topic as the comic, since the attempted savings isn't time, it's saving personal energy expended by walking. It's shifting costs from personal energy to personal time, to achieve a substantial savings of personal energy.

No, it's making a decision based on sunk costs. I've spent ten minutes looking for a parking space, it would be a shame to park so far away now, let's look a bit closer. The more you invest, the more you feel you lose by just parking in the reasonable space.
And if you figure ten minutes walking is a substantial expenditure of energy, that's pretty sad. I never thought I was in especially good shape, but wow. "I can't walk a half a mile, it's too hard". Wow.

Strictly speaking, on a purely monetary basis giving to charity means you're working for nothing, because you are handing out money for nothing of any material value in return. All you get in return is a good feeling, which, being priceless, makes it financially worthless.

Do the math again. It's financially worth exactly what you paid for it, to you. If it weren't you wouldn't have paid for it, voluntarily and with full information about the transaction. You can't transfer it, but neither can you transfer the fitness you buy at the gym or the massage you get from your local masseuse. You wouldn't say those are worthless, would you?

[philsov]

"I drive instead of riding a bike because there's too many cars on the road" ... okay, I can buy that, but it still makes no sense.

It makes plenty of sense. The closest gym to here involves me getting on the interstate. In the case of a bicycle or walking I suppose I could travel along the shoulder of the service road, but that's seriously putting myself in harms way. There are no bikelanes, no sidewalks, and cars traveling at 60 mph.

Biking to the gym is significantly putting myself in danger for the sake of personal well being. THAT makes no sense.

[bmonk]

Someone made a very similar argument to me a few years ago when I chose to take a slower train route that saved me £10 (~$15) but involved hanging round a station for half an hour. His precise response was along the lines of - "yeah, OK, you're valuing your time at £20 an hour, seems reasonable."

To be honest it had never struck me to think of it in that manner, I'm not sure I still do. After all, it's not like I spend all my time attempting to eek out extra productivity. Also, this cartoon (and that statement) presume:

* that you would otherwise be engaged in some sort of economically productive activity
* that there is no extra value to making the journey

I'd argue that the first assumption is flawed - to take my train journey, I'd have only arrived home an hour earlier and sat of my arse in front of the computer/tv.

The second ignores all of the potential psychological/well-being benefits - whether it be the satisfaction of saving the money (clearly valuable to some judging on this thread), or simply leaving the house for twenty minutes when you're bored. These provide gratification, which promote well-being, and thus increase your productivity and capacity when you are working.

To say that if you travel 9 minutes to save a dollar, that you are therefore working for ~$6 an hour, and therefore working for less than minimum wage, might be superficially true but misses the various qualitative benefits that the activity might bring.

More, I used to commute to school by train--and that meant I had 40 minutes (or more) each way to read in mostly undisturbed comfort, since I rarely went during rush hour, and even when I did I could usually find a seat. So the time spent commuting didn't matter--it reduced the time spent studying in other venues.

That's kind of like buying gas at the cheapest place on your route--as long as you are making the trip for some other reason, stopping to buy gas is not going to add expense.

I think I only just learnt it lemmings.
On car related maintenance. It's "cheap" to fit the parts yourself. But the garage still charges you to adjust everything back to the correct settings.

It reminds me of an old joke about someone who went to a garage because his car broke down.
The mechanic tooke a look at the machine, took his hammer and gave it a little thump and the machine went like new.
After he was charged 10 [enter your favourite currency] the man argued: "You only gave a little thump!"
So he got a bill:
"Given a thump: 1 [enter your favourite currency]
Knew where 9 [enter your favourite currency]"

LOL! My Dad once went in on a weekend to solve a rush problem for a company--the other company had worked three weeks, using 95% of the sample, and gotten nowhere. He was able to solve the problem in 5 or 6 hours, on a Saturday. When the other company suggested that $10,000 was a bit steep for that quick work, he replied in much this joke's manner--you are paying for the expertise that your own people apparently lack. I did you a favor, kept you from spending another $50,000 without results and idling your production in the bargain. $10k is cheap.

[jpk]

"I drive instead of riding a bike because there's too many cars on the road" ... okay, I can buy that, but it still makes no sense.

It makes plenty of sense. The closest gym to hear involves me getting on the interstate. In the case of a bicycle or walking I suppose I could travel along the shoulder of the service road, but that's seriously putting myself in harms way. There are no bikelanes, no sidewalks, and cars traveling at 60 mph.

Biking to the gym is significantly putting myself in danger for the sake of personal well being. THAT makes no sense.

That's problematic. Somewhat different from "there are fumes", though. If you live where there's no gym within bicycling distance, and you have some reason to live there instead of someplace where you can live a healthy and active life, then I guess you're stuck. I notice you only mention the closest gym, which seems a curious constraint on someone who's going out of his way to enforce a certain amount of exertion in his day, but I'll assume there's no gym within ten riding miles of you, and therefore that you don't live in an urban or suburban area in North America... in that case, you chose the rural life for a reason, I guess.

[MrRubix]

The problem is that after a certain point, optimizing your time is needlessly difficult depending on what you want to get done and how far ahead you want to look. Depending on how adept your mind is naturally, there's a certain level of heuristic judgment that you are comfortable with with respect to decision making and utility, even if it's not rational. Blame evolution if you want to.

[Infiltrator]

This one confused the crap out of me until I realised you were talking about gallons... ten cents a litre is quite a good saving; that's $7.20 for me; which translates into about 55km. Which is much farther a mile; thus it being worth driving two clicks down the road to get the cheaper petrol.

[NiteClerk]

A different point of view: My neighborhood gas station is sometimes (but not often) 5 cents higher than the big box on the corner of the highway. I buy about 20 U.S. gallons per week for my truck. So what if I spend an extra $1 per week? That's $52 per year. Big deal. The family who owns the local station gave $50,000 to my kids school during a fund drive once. Plus they keep their corner clean and well lit.

It's not just about the money.

[philsov]

but I'll assume there's no gym within ten riding miles of you, and therefore that you don't live in an urban or suburban area in North America... in that case, you chose the rural life for a reason, I guess.

Any gym that isn't something like an appointment-only personal training studio involves me getting on or intersecting the interstate or getting onto a 4+ lane road that intersects said interstate -- all of which lack sidewalks, bikelanes, and feature 60 mph cars. It's 2.5 freaking miles away but there is no safe/back way to get there that isn't a motorized vehicle. God bless Houston suburbs with subdivisions that spit out onto major thoroughfares.

[keiranhalcyon31]

... --such as the fact that bicycles are road vehicles and do not belong on sidewalks-- ... [and commit a crime doing so] ...

The only crime here is that it's considered a crime to ride a bicycle on the sidewalk - especially if the road conditions are such that the danger to pedestrians from bicycles on the sidewalk is less than the danger to cyclists on the road from motor vehicles. And if a cyclist is inconveniencing traffic by more than a few seconds, the cyclist is doing it wrong.

[JudeMorrigan]

That's problematic. Somewhat different from "there are fumes", though. If you live where there's no gym within bicycling distance, and you have some reason to live there instead of someplace where you can live a healthy and active life, then I guess you're stuck. I notice you only mention the closest gym, which seems a curious constraint on someone who's going out of his way to enforce a certain amount of exertion in his day, but I'll assume there's no gym within ten riding miles of you, and therefore that you don't live in an urban or suburban area in North America... in that case, you chose the rural life for a reason, I guess.

Erm, it's entirely possible to live a healthy and active lifestyle while living someplace without a gym within a reasonable bike route to it. This is kind of the flip side to my statement to keiranhalcyon31. Sure, there's a gym ~3.5 mi from where I live, but if I were to make that trip on a consistent basis on the roads I'd have to take, I'd consider it only a matter of time before I got in a fairly serious accident. It's somewhat irrelavent in my case anyways. I maintain a healthy and active lifestyle via ballroom dancing, and there really isn't a studio within bicycling distance of where I live.

... --such as the fact that bicycles are road vehicles and do not belong on sidewalks-- ... [and commit a crime doing so] ...

The only crime here is that it's considered a crime to ride a bicycle on the sidewalk - especially if the road conditions are such that the danger to pedestrians from bicycles on the sidewalk is less than the danger to cyclists on the road from motor vehicles. And if a cyclist is inconveniencing traffic by more than a few seconds, the cyclist is doing it wrong.

I should post a picture of my elbow one of these days. The scar tissue there is fairly spectacular. Suffice it to say that sidewalks also have the issue of curbs, which can be quite hazardous to bicycle riders. Admittedly the accident in question involved some fairly epic stupidity on my part, but the bottom line is that if I'd been riding in the road where I belonged, it never would have happened.

Also, your last point depends heavily on the road in question. Sometimes there really isn't an alternate route, and a cyclist gets stuck on a trafficed two-lane road. I can assure you, the cyclist isn't enjoying things any more than the motorists are.

[jpk]

but I'll assume there's no gym within ten riding miles of you, and therefore that you don't live in an urban or suburban area in North America... in that case, you chose the rural life for a reason, I guess.

Any gym that isn't something like an appointment-only personal training studio involves me getting on or intersecting the interstate or getting onto a 4+ lane road that intersects said interstate -- all of which lack sidewalks, bikelanes, and feature 60 mph cars. It's 2.5 freaking miles away but there is no safe/back way to get there that isn't a motorized vehicle. God bless Houston suburbs with subdivisions that spit out onto major thoroughfares.

Sounds awful. You have my sympathy - I thought Boston was bad, with the drivers we have here.

[bobtpawn]

One of the advantages of being a mathematician is that I can do research while I drive. Thus, going slightly out of my way for gas is effectively double-billing my time.

[jpk]

... --such as the fact that bicycles are road vehicles and do not belong on sidewalks-- ... [and commit a crime doing so] ...

The only crime here is that it's considered a crime to ride a bicycle on the sidewalk - especially if the road conditions are such that the danger to pedestrians from bicycles on the sidewalk is less than the danger to cyclists on the road from motor vehicles. And if a cyclist is inconveniencing traffic by more than a few seconds, the cyclist is doing it wrong.

It is actually fantastically dangerous to ride on the sidewalk if you're actually going somewhere, because it involves popping in and out of traffic at intersections and other random points. If you're riding for transportation your only safe option is to ride in a bike lane if there is one, or in a full lane of traffic if not.
Breaking traffic laws because you can get away with it is also dangerous. You want the other traffic to be able to predict your movements and plan accordingly. Bikers who run red lights because they don't see any cross traffic, or jump the gun when they see the cross signal going red are injecting chaos into an already difficult situation, with potentially fatal or injurious results. I'm always amazed by this, because the person most at risk is the one on the bicycle, so you'd think they'd realize how stupid they're being. Especially when I pull up next to them two minutes later, having gone through the intersection safely and legally.

[Daggertrout]

I get gas at a station where there are three others right next door. I always go to the Sunoco since they tend to be about $.02 more per gallon, so they'll be practically empty while you can't even pull into the others.

[rhomboidal]

Just as important in my choice of gas stations as the price of the gas: the price of the Red Bulls.

[thp]

Time=money, generally that's true. In reality however, some bosses just won't pay their employees more then the aforehand agreed (40) hours per week. So if folks want to earn/save more money, they'll have to settle for less.

[cream wobbly]

Wow. You just worked this out, Randall?

As others have pointed out, you also have to factor in the wait at a station with cheaper fuel.

Aside from that, you have to consider the fuel wasted waiting in traffic around a station that can afford to make a lower profit margin per unit of fuel. The high-traffic is precisely why the fuel is cheaper at that location: they sell more fuel.

[cream wobbly]

I'm always amazed by this, because the person most at risk is the one on the bicycle

Here in Tucson (where fuel is about the cheapest in the country, btw), we get cyclists going against the flow of traffic. We also get wheelchairs in the cycle lane -- again, often with the kerb to their left.

So, I'm turning right in my car. I watch left, because that's where I'm looking for an opportunity to merge with traffic. Idiot cyclist comes up on my right just as I'm dropping the clutch (along with the none-too-discreet sound effects of a turbodiesel engine). Idiot cyclist decides to swerve in front of my car rather than just whump into the side. Heart-attack triggers my right foot on the brake pedal. He gets to live another day.

Meanwhile, my schnout is sticking out into traffic now, and the lunatic in the pristine white F150 behind me has closed the gap...

Sigh.

[very-jaded]

I like the statistical rule-of-thumb for finding the cheapest gas. Once you decide to buy gas (perhaps when one quarter of your tank's capacity remains,) take note of the cheapest gas you see during the first sixth of the total distance remaining in your tank. From the second through the fifth sixths of your trip, as soon as you see gas priced at or below the cheapest price, buy it. If you haven't matched the lowest price by the time you get to the last sixth of your trip, buy gas at the next station you encounter.

Of course, this assumes a fairly even distribution of desirable and safe gas stations along the route, and that you're smart enough to fill up before your tank is dry. But it's a better strategy than nothing.

I don't know what kind of gauge you have that lets you divide the last quarter of your tank into sixths accurately enough to do this...

Besides, none of this affects me. I put in €20 worth whatever the price, so it's the same wherever I fill up.

<ducks and runs>

I know that when my tank reads 1/4 that I have about 60 miles to go before it hits E. The math is really simple then. I can spend the next 10 miles scanning for the cheapest price, and then have 40 miles to drive past a station selling at that cheapest price; or else there's a bit of panic because I better find a station in those last 10 miles.

But since I started doing this I've switched to riding the train, which takes me on a much shorter and different route where I pass only three service stations to and from the station, all across the same intersection from each other so they all match each others' prices. :-/

[unus vox]

Not caring where I get my gas from and just going to the nearest gas station is the best investment I've ever made. For people who actively worry about spending an extra dollar a week on gas, and meticulously plan out routes to save said money... well, therapists cost hundreds of dollars, compared to my $1.00 deposit of not giving a $#!^.

[Atticus]

You can easily up your earnings through scale, just brink lots of extra containers and buy your gas 100 gallons at a time.

[Yosarian2]

It's worth mentioning that the fact that people are willing to go out of their way to get cheaper gas provides a much higher competitive incentive for gas stations to lower their prices.

If everyone just bought gas wherever it was continent and ignored the price, then logically speaking the price that everyone pays at the pump would most likely go up significantly, because it would then be more profitable for gas stations to charge more, rather then constantly fighting to undercut each other.

[blyerkit]

Hi everyone! Just from the economics point of view (I'm not an economist - I'm a musician... I just read a lot, OK?), this doesn't seem to take account of whether or not you would have spent the time anyway (in which case it ceases to be a factor), and/or whether it is really valid to count the value of non-earning time as the same (or more or less than) earning time. Is it possible (or at least humanly accurate) to measure the value of leisure time financially?
Having said all that (with the help of half a bottle of shiraz), I live in Poland, where the economics of personal motoring seem even more irrational than in my native England. Here, cars are tremendously expensive relative to the living wage, and fuel (though cheaper in absolute terms) is similarly relatively more expensive than in (for example) the UK. Nevertheless, people on the whole drive as if their cars are both cheap and indestructible and fuel is free, the cost of which makes the whole "penny-saved" argument seem somewhat irrelevant.
PS I discovered xkcd only a couple of weeks ago, and I don't even want to begin to think of the economic implications it has had in terms of my personal productivity, nevertheless I am happy with the discovery.
PPS for those of you who want to do the comparative math, fuel (averaged) over here costs around 5.15PLN (~$1.60) per litre (NOT per gallon).

[Eebster the Great]

Unless your time would otherwise be spent earning money then in a situation where driving to the other station is saving money on the total fuel cost it *is* better to make the trip.

Unless you value your time . . .

[cardiff space man]

I buy my gas at one end of my commute or the other, depending on which end is cheapest. The cost to deviate from the commute to use the station is minimal, so any difference is exploitable.

I wish there was more price sensitivity in my town, not less. Our prices are higher than those in "the nearest big city in my region", and this area itself has over a million people. (So by big city, I don't mean Eugene OR for example).

[astrosteve]

I feel like this comic is about my mother, I really do. The _only_ thing that matters to her is how much money comes out of her pocket. Time, travel expenses, etc. are meaningless to her. She's extremely short sighted in that sense. She recently got a coupon for $10 off any item at some store around here. She went out and bought something she didn't need just so she could talk about how much money she's saving.

I once suggested that, by her logic, she should be driving to New Jersey every time she wants gas because it's cheaper there than anywhere in this state. Interestingly enough, instead of trying to respond intelligently, she just said, "Stop being stupid." Ugh.

[Tony]

`

This actually reminded me of a thought puzzle I was contemplating while on a road trip over Labor Day:

Say you're on a Road Trip. You are 300 miles from home. The gas station on the corner is selling gas at $3.00/gallon. Every mile, there is another gas station, each selling gas for an additional $0.01/gallon. So after driving 1 mile, the gas station there is selling for $3.01, and the gas station next door to your house sells gas for $6.00/gallon.

You start your journey with a full tank of gas (for ease-of-math sake, 10 gallon tank). You get 30 miles/gallon, so you can make the entire trip (ending on fumes) on a single tank. However, you want to be sure that you have a full tank of gas when you leave for work in the morning, so you must refill it at the station next to your house.

What's the cheapest way to end up at home with a full tank of gas? Where should you fill up, and how often?

Does the answer change if you start with an empty tank of gas and have to decide how much to put in the tank to begin with?

I believe that, given the following factors:

c = capacity of gas tank
d = distance between stations
e = # of gallons of extra gas expended to stop at a station and accelerate back to highway speed
g = # of gallons of gas currently in the tank
m = current fuel usage in miles per gallon
p = price of a gallon of gas at the next station
q = price of a gallon of gas at the station after that

You should only stop when one of the following conditions are met:
1. (q-p)(c-g) > pe -- the amount saved by stopping at the next station is greater than the cost of stopping, or
2. d > gm -- there isn't enough gas in the tank to reach another station.

I ran a quick simulation and confirmed that e is the interesting one. Using reasonable values for it I got a total cost of about $76.50, filling up every 17 or 18 miles and then again upon arrival.

I enhanced the simulation by making gas mileage improve as the fuel load is used, and as long as the variance isn't extreme, it always makes sense to fill the tank to capacity whenever you stop. In more extreme cases, it's more economical to carry less fuel and stop more frequently.

Thanks for the interesting problem!

[neoliminal]

For Bill Gates, it is cheaper (for the price of his time) to own every gas station on the most likely routes he would ever take. Should he ever run out of gas, he could simply offer $10,000 to rent a random stranger's car to his destination, assuming it was more than a 30 seconds away and still be on the positive side of the equation. In fact, writing the check would cost him more than the check.

We all have different levels of what qualifies as reasonable use of our time, however we do not all have a reasonable number.

[marcel]

I'd just like to point out that you Europeans are pretty much screwed. Here in Texas, we pay $3.449/g; which Wolfram and Google both tell me is .6599 Euros/liter.

We maybe screwed in gas prices here, but that is compensated by travel distances and necesity of using a car. The average car user here will be using a lot less fuel than the average Texan car user, probably enough to negate the fuel price difference.

[Belgand]

This is why it's so important to do what you love -- you'll never work a day in your life.

The problem with this is how quickly it turns into you hating the thing you love to do. You'll spend hours and hours on a hobby because you choose to do it and enjoy the time you put in. The problem occurs the second you're suddenly required to do it and don't have the option to just choose not to.

Put it this way, you're now a paid moderator for this forum. It is your job to spend eight hours a day reading, responding, filling out reports, etc. You cannot decide that you want to do something else. If a friend calls and wants to go do something you have to say "Sorry. I've still got a few more hours of reading forums." It becomes a burden and now you hate something you enjoyed.

It's not always true, but I've heard this sort of thing a number of times from writers, critics, and other people who work doing something they formerly enjoyed.

[Eebster the Great]

I'd just like to point out that you Europeans are pretty much screwed. Here in Texas, we pay $3.449/g; which Wolfram and Google both tell me is .6599 Euros/liter.

We maybe screwed in gas prices here, but that is compensated by travel distances and necesity of using a car. The average car user here will be using a lot less fuel than the average Texan car user, probably enough to negate the fuel price difference.

In the U.S., we also pay for this difference—at least to some extent—in our taxes, as gas is heavily subsidized.

[metafor]

And if you drive to the gym, you're paying money to drive to a place where you pay money to ride on a pretend bicycle.

Hopefully that's not all you're doing at the gym or else you really would be wasting your money/time. But really, assuming one is a consistent exerciser, the gym is never cost-efficient compared to home exercise. The only thing a gym might have over home workouts is atmosphere.
Now how much money are we all spending by being on this forum?

Assuming you've already put down the capital for adequate space (i.e. a house or large apartment) and the equipment (dumbells, chairs, treadmill/bike), how long will it take to recoup the cost compared to a monthly fee? Even assuming the equipment you use at home doesn't have to be as expensive as the ones available at a gym.

Also take into account certain facilities such as indoor basketball courts, swimming pools, etc. that may be available.

Add to that that certain places in the world simply aren't suitable year-around for exercising outside (such as running, biking, etc) and all of a sudden, it doesn't seem so cost-inefficient to pay a monthly membership fee.

[A_of_s_t]

Ten cents cheaper? Holy crap, I'm going over there if its not out of my way.