[mamelukesabre]

A better method would be to start the test with a full tank of gas and batteries exactly half charged. THen end the test when the tank is dry and the batteries are exacly half charged. I don’t know how you accurately determine “half charged” though.

The reason I say this is better is that a hybrid gets it’s fuel economy by switching back and forth between gas and electric depending on driving conditions. If you start the test with ZERO battery power available, you are killing the hybrid effect and hamstringing the car’s max potential efficiency in the earlier miles in the test.

[HundredDollars]

Determining half full would be a problem. My intention was to run enough tank fulls that the first recharging inefficiency would become insignificant.

Maybe the best test would start and end with the battery fully charged by the engine only.