Noticed this too, my understanding is that we have a saddle tank and it pools on one side then settles out later. I would "lose" about 1/4 tank when I got off track. My other car does not have a functional fuel gauge at all so it isn't that big a deal now that I know 2 session = fill it, but it is a bit odd they didn't take it into account since it is a race car with a plate Guy I was pitted next to in a C5 Z06 said his car has pumps to even out the bags, but he has had them fail a couple times.