Right guys. Filled my 08 Prius up for the first time today. I plan to reset trip A every time I fill up and to use trip B as 'total mileage covered' since I bought it. I wanted to do an average mpg between fill ups, and an average lifetime mpg - is this possible? When I reset trip A today it reset the average mpg on the screen too. I thought If I switched to trip B then it would show an overall mpg but this was also reset. Hope this makes some sort of sense :-/
On the Gen 2 Prius, there isn't a way to track both as far as I know. The MFD only has the ability to track fuel economy for either a tank/trip basis or for as long as you want before you reset it.
I use A for that days MPG and B for the tank full. There are smartphone apps like Fully that are very good.