I recently borrowed my in-laws’ SUV for the 4WD in order to transport my family to Christmas at my family’s house during a smedium Midwestern snowstorm. They borrowed our sedan in return. When we returned the SUV, I insisted on filling up the tank even though it was only half full when we took the car. My wife told me I was being foolish and was under no obligation to fill the tank before returning the car because they had ours at their disposal. I believe as I was the one who requested the trade I should fill the SUV’s tank before returning it. My question is: Am I a sucker or following good form? Also, should the in-laws have filled our tank as well?
I withdraw the second part of the question. I don’t think my in-laws were under any obligation to fill our tank.
I always return borrowed cars with a full tank. I also appreciate someone who fills up a car borrowed from me. I just think both practices are good manners.
I agree with jayhawkroy.
Borrowing someone’s car/truck is certainly a whole lot cheaper than renting one. The borrower should at least fill the tank of the borrowed car prior to returning it, in order to show appreciation for the courtesy that was extended to him/her.
Edited to add:
This should not extend to “loaner cars” from a dealership or a mechanic’s shop.
In that type of situation, I note the amount of gas in the tank when I receive the loaner, and I add enough gas before returning it so that it has the same amount (or perhaps slightly more, since it can be difficult to estimate the correct amount) in the tank.
I would never return a car that was loaned to me by a relative, friend, or just a kind individual, without filling the tank. If I got it dirty I’d also clean it too. You did the right thing.
Agree; it’s common courtesy to fill the tank, wash the car if it’s dirty and make sure the oil and wiper fluid are up.
Some time back I borrowed my father-in-law’s Buick station wagen which had all the trailer towing equipment. We took a 7000 mile holiday trip with our camper in tow.
I replaced the front brakes, in additon to doing all the above things mentioned.
I’m with you. I’d return it washed and vacuumed with a full tank. You didn’t say how far you drove, but remind your wife that you may have used up some of their oil life and generally depreciated the car a bit with the additional mileage.
The way I see it - unless you made an unusual deal, you borrowed the car, not the gasoline in the tank. Returning the car clean and with a full tank of gasonline is the very least you can do to show your appreciation.
You are a thoughtful FIL and may be rewarded in the future with other opportunities to borrow the SUV. Your SIL should put you even higher on the Good List that you were before. I’ve only borrowed lawn mowers, but I always return them with a full tank of gas, even if they were empty when I borrowed them. If your wife wants monetary justification for your generosity, tell her that the IRS authorizes $0.55 per mile reimbursement. On that basis, you only have to go 90 miles to equal $50.00.
Just leave a few bucks in change in the ashtray (along with the butts you smoked in the car). You don’t want to spoil the inlaws do you? 
Anyone who loans you a vehicle to drive during a snowstorm because it’s 4WD deserves a full tank of gas…and more. A wash job, a vacuuming, and even a generous gift certificate to their favorite restaraunt. The circumstances involved raise this kindness to beyond a normal loaned car.
He never said he was the Father in law.
The IRS deduction (not reimbursement) is irrelevant in this case.
*55 cents per mile for business miles driven
*24 cents per mile driven for medical or moving purposes
*14 cents per mile driven in service of charitable organizations
Also it should be noted that the amounts have been revised as of Jan. 1, 2010.
You did a good thing. What’s wrong with the wife? Don’t second-guess yourself when you do good stuff. Cowboy up.
“The IRS deduction (not reimbursement) is irrelevant in this case.”
I write off my personal mileage on business trips at $0.55/mile and I am reimbursed for it by my company. If I owned my own business, I could deduct the mileage allowance from my company’s earnings, which is a reimbursement as well.
In the context in which the suggestion was offered, it is relevant.
I have a car that you can borrow and you don’t have to return it with a full tank. The only proviso is that you don’t return the car at all. This would make my wife very happy.
I think you did the right thing.
I am so old school I was always taught to return a borrowed item in better condition if possible.
Your proposal intrigues me. which one is she wanting you to get rid of? 
The car is a 1978 Oldsmobile Cutlass Salon with the 4-4-2 trim. I bought the car new and have maintained it through the years. However, at this point, I can’t keep up with the tin termites. It needs to have the floor panels patched. Seventeen years ago, I let my son take the car to college. However, in his sophomore year in college, he went on an Appalachian studies semester and I thought he should have a better car, so the Oldsmobile came back. I gave it to a person in an old car club, but his wife said he couldn’t have another old car and brought it back. A couple of people offered to buy it, but then after making the offer, they didn’t show up with the money.
Unfortunately the 4-4-2 was just a trim package in 1978. The engine is a 260 V-8. It has a single exhaust and an automatic transmission. I thought it had been stolen a couple of years back. I was driving along in my minivan and I saw the car go flying down the road. However, my wife had a flat tire on her car and was using it. I tried to trade it back in December of 1995. The dealer wanted $14,500 for the car that I was going to buy if I traded in the 1978, and $14,200 if I purchased the car without trading in my 1978.