If there is an agreement up front about the fuel expense then you should stick to the deal, if not then sorry about your luck. I had a deal to sell a car a few years ago. I provided the buyer with all the pics he requested and he sent me a $250.00 deposit because it would be a few weeks before he could get the car. We finally got together on a date and he asked if I could meet him 1/2 way. I agreed to and he offered for me to keep the deposit if he didn't like the car when he saw it. Of course that didn't happen because I was honest about the car and he brought the cash we had agreed on.