Newbie wrote:
> It may seem like a superfluous question, but what is the best way of
> calculating what mmg yuor vehicle is getting? I have my miles reading
> of course, and I can record how much gas I put in, but there was some
> gas already there in the tank, and how do I know what was traveled on
> how much gas? If you have a good system, please share!

One normally assumes that the tank becomes equally full right after each
fill-up. Therefore, all you need to do is reset your trip-odometer after
each fill-up, but first, divide the number on it by the number on the
pump. (In other words, the amount of gas you just put in equals the
amount you used between the previous fill-up and this fill-up.)