How would I be able to experimentally test the efficiency of conventional and alternate sources of car fuel?

We are trying to determine the efficiency of unleaded gasoline, pure ethanol, 10% ethanol, B20, and B100 (using Jatropha biofuel). Most likely, we will try to use a basic self built calorimeter to test for how long the fuels burn, how quickly they reach their maximum heat (and what that maximum heat is), the time [...]

How difficult/expensive would it be to convert an RV with a gas engine to a diesel that runs on biofuel?

As soon as bio fuel is available for everyone to pump into their vehicles would any of you choose biofuel?

Why? Or why not?