Did I give her the right amount of gas money?

It's not just gas money, it's also the hassle of going to your house and picking you up and stuff. You paid less than it would cost to take a shuttle.

hahahahahaha. you got screwed. Round trip probably cost about 10-15 dollars 100 miles, guessing the car gets about 30mpg, would mean it used about 4 gallons (rounding up). 4 gallons x $3.00 = $12.00

personally if you figure in that you get about 30 mpg on the highway or 18ish in the city you actually gave her far too much.

I would say that's fair, if you would have rode in a taxi it would have been doubled. It costs $70.00 here in a taxi just for 30 miles so I guess you got off easy.

She totally screwed you. My Jeep would cost less than half of that.

100 miles? Well, thats a big favor to ask of someone so i would generally say whatever she wanted to charge you is fine. Although i would not have charged a friend that much myself. A car like a Honda Civic, it probably gets in between 30-35mpg. Lets just say the car gets 30mpg, your friend would have used around 3.5 or maybe 4 gallons of gas at the most on the trip. Now lets say gas is at the most 3 dollars a gallon . 3x4=12. It cost her 12 dollars in gas if my math and facts are right. Lets just say 15 if im off somehow. You also have to consider in the fact of when you ask someone to do something like that, as i said its a big favor. So of course you have to understand you are gonna have to pay them for the time and effort. For instance, when you got there did she have to wait a few hours or any amount of time for you to take care of your business before you were ready to go back home? Still, 60 bucks is allot to hit a friend with. I would have driven a friend there for 25-30 and maybe had them pick up lunch.

$60 would give her 2 full tanks of gas, which is probably around 500 miles. ask for $25 back.

It probably cost her about $10.00 in gasoline for such a return trip. Use mapquest, it has a fuel cost calculator and you can look up the mileage that a vehicle gets on the web. I hope she paid for the happy meal. The IRS uses the guideline of $0.55 per mile for business use which includes not only fuel, but depreciation and maintenance of the vehicle as well as the time required to drive it so $55 would seem to be a fair price, if such driving was expected to be a source of income for her. The IRS rate for medical and moves is $0.24 per mile and for charities is $0.14 per mile so if she was only asking for gas money (that is her time is being donated) then $14 would be more reasonable and $24 if her time is to be valued but there are compassionate reasons for providing the ride such as providing a ride for a friend. What she charged can be considered fair if your relationship was just that of a co-worker or an acquaintance but a friend should've charged less.