[On the Road to Serfdom]

I think Hyprids are allowed cheat in the tests, by having their battery end the test at a lower charge than at the beginning. They only measure gas used during the test.

[Eagles Talon IV]

I don't see where that matters. The test is how many mpg does the hybrid get in under the conditions tested. You or i needn't know nor should we care about the battery's level of charge before during or after the trip.