Help me settle this mileage debate

Wife's Caravan 20 gal tank @ 18 mpg combined, my F150 18 gal tank @ 14 combined according to fueleconomy.gov

Grocery store points system gives us gas rebate but points are at zero after each fill-up and gets built up as we shop. Reg gas price is $3.32/gal. Points price is $2.70/gal.

Who's vehicle makes more money sense to fill up at the lower price. We drive quite similar numbers of miles weekly so that's a draw.

We each think it makes more sense to fill our own tanks... Can anyone clear this up because my brain hurts.

Is this disagreement with your wife? If so, I have no advice for you.

Either way, it's money not coming out of your pocket, so you win.

The truck, bring jerrycans, truck hauls jerrycans better.

Yes, with the wife! But it's the strangest thing. Either one of us can be right and the other will be ok with that! Weird right?

Gas mileage doesn't matter, you are trying to get the most gallons per pump because your per gallon discount goes away after each pump so you should use the points on the larger tank.

So...

The van takes 20 gal., saving .62 cents per gallon, filling it completely (and thus resetting your discount to zero) saves you $12.40.

Your truck takes 18 gal, times the same .62 cents, filling it completely (and thus resetting your discount to zero) only saves $11.16.

Since the "fuel points" are obliterated with each pump, i.e., you don't get X number of gallons for .62 cents off, you get .62 cents off on each pump, you should fuel the bigger tank, MPG's, driving distances, etc. are irrelevant.

EDIT: Of course, the numbers are so close that the answer is probably, "whoever drives by the store frequently enough that they will use all the points without letting them expire or having to go out of their way."

At least you're getting more out of it that us, my Fit has a 10 gal. tank and my GF's Civic... 11 gal. :-(

Well, since the truck gets worse mileage, it will obviously use more fuel mile-per-mile vs. the van, thus you would realize greater savings per mile by filling up the truck with cheap gas.

However, without knowing the average mileage driver per tank for each vehicle, we can't compute the total cost per vehicle to know where the most savings would be realized.

Make sense?

I've got a similar deal at the local grocery store, however, discount only goes for 15 gallons.

petegossett wrote: However, without knowing the average mileage driver per tank for each vehicle, we can't compute the total cost per vehicle to know where the most savings would be realized. Make sense?

Can we just say they are identical and go from there?

Whichever one lets you keep your hootus at the end of the day.

The one with the most empty tank.

Bring both cars. Don't hang the pump up. Duh. Not anecdotal. We do it, because I'm a cheap c*nt. We also coupon like crazy, fill out the "customer service surveys" for bonus fuel points, and buy Kroger gift cards for shopping when they do a double or triple fuel point deal.

I haven't paid over $3.00/gallin in months. It's free money.

In reply to wlkelley3:

... or the one with the big auxiliary tank and transfer pump in the bed .

ebonyandivory wrote:

petegossett wrote: However, without knowing the average mileage driver per tank for each vehicle, we can't compute the total cost per vehicle to know where the most savings would be realized. Make sense?

Can we just say they are identical and go from there?

We can say it doesn't matter.

NOTE: I guess I'm assuming that your system works approximately like Kroger's here in Ohio. You get like 3 cents off for every $100 you spend in groceries (those numbers might be hilariously far off, but that is the basic concept.)

So, you spend your $100 and get your 3 cent discount.
You can use that 3 cent discount exactly once, for one fill-up, before it expires.
If you use the discount on a car that gets 10 mpg and has a 10 gal. tank, you save 30 cents (3 cents X 10 gals.)
If you use the discount on a car that gets 30 mpg and has a 10 gal. tank, you STILL save 30 cents (3 cents X 10 gals.)
Just because you were able to drive further on that 10 gal. (lower "savings per mile") doesn't mean you saved less IN TOTAL.
TL:DR: MPG's don't matter.

Now, let's say you spend your $100 and get your 3 cent discount again. Same deal, you can use the discount for one fill-up, then it goes away, and it will eventually expire. If you use the discount on a car that you drive 100 miles a day, gets 10 mpg, and has a 10 gal. tank, you drive enough to save the 30 cents per fill-up EVERY DAY, BUT you would have to also buy another $100 of groceries the next day.
If you wanted the same discount you could have just bought $200 of groceries on the first day and bought 10 gal. at a 6 cent discount. As long as you drive enough to use up the points before they expire it does not matter how much you drive.

The only important value (as long as you're driving enough to avoid letting points expire) is tank capacity. MPGs, total miles travelled, your lucky number, the birthday of your maternal grandmother are all irrelevant.

BoxheadTim wrote: In reply to wlkelley3: ... or the one with the big auxiliary tank and transfer pump in the bed .

They usually max out at a dollar or gallon amount.

We get 20 cents a gallon off for every $50 we spend at the grocery store. If the Focus and the wife's Legacy both need gas we use the discount on the Legacy always.

Reason: The Legacy has an 18 gallon tank and the Focus is only 12. Sometimes I take along two 5 gallons cans which works out great since there is a 30 gallon limit.

Plus one on the gas cans.

Buy gift cards if they count toward grocery purchase.

wlkelley3 wrote: The one with the most empty tank.

Yep, that. And don't forget the gas cans.

We almost always save them up and then full the Suburban and it's 37 gallon tank. They cut off the discount at 30 gallons, and we never have a problem maxing it.

buy a bigger truck with a bigger tank. i fill my avalanche, they cut it off at 30 gallons but the discount can be used up to and including free gas. i've gotten 7 or 8 free 30 gallon fill ups. i take gas cans in case i'm not low enough to get to 30 gallons.

The local gas station did a "buy a car wash at $5.00 and get $0.20 off. They put a maximum usage of 20 gallons after my dad bought a wash, gave the ticket to me, and filled both 50 gallon tanks on the dump truck.

I think poop has the right idea.

gofastbobby wrote: Is this disagreement with your wife? If so, I have no advice for you. Either way, it's money not coming out of your pocket, so you win.

Ah, but it is coming out of your pocket in the form of higher food prices. This is literally the 21st century version of S&H green stamps. Grocery stores would give out stamps that one could redeem for merchandise. The rub was, higher food prices paid for the merchandise so, even if you did not participate, you paid more and helped subsidize the people who did collect the stamps.

So Mr OP, the price of gas is exactly the same. You just prepaid part of it. Be magnanimous and give the, er, "discount" to your wife knowing it doesn't make a damn bit of difference.

Damn, you guys are making me really glad we have electric cars.

Bryce

Well, you are both right or, more precisely, wlkelley3 is right. Fill up which ever has the higher capacity for fuel storage. I would get a 20 gallon drum to throw in the back of one of those cars as well to full up completely. So, the actual answer to your question is which one can hold more gas cans?

patgizz wrote: buy a bigger truck with a bigger tank.

I have an aux gas tank but its leaking so I can only use one until I can replace it. If I had use of both tanks, I'd win this debate hands down.