<prompt> Human: Im doing the occasional business travel for a company not commuting. It looks like a typical drive will be 50-100mi away variable in my 25-30mpg personal vehicle. They are offering to buy a tank of gas for each trip.They arent being stingy per se, but Id rather they just pay the IRS mileage rate which seems more fair for all involved. For this particular trip, theyre paying about 0.10mi less than the mileage rate, but for shorter trips, they might end up paying slightly more.Maybe Im being nit picky, Id just rather not calculate each time if Im being screwed or not. I also wont feel the need to run down my tank before filling up and expensing it, in order to get the most out of their offer. Should I try to convince them to do IRS mileage? Is there any legal stuff involved?  <response>: The IRS mileage is the way to go. The mileage estimate includes projected maintenance costs to the car, not just the price for gas, so you get more back and hopefully cover the wear and tear on your car with it. 