I'd like to know if you guys find this is a good idea. I like being able to compare fuel prices to what they were X months/years ago. Therefore, I would like having a feature where I could compare my running average in a graphic with the possibility of adding one (or many friends) in the graphic so you would have a concrete idea of who's getting better mileage at certain times.
I'm not quite sure what you're after. You'd like a chart that shows the price you're paying for fuel compared with your friends? That's not going to be a fantastic comparison unless you and your friends have exactly the same model and similar driving conditions.