A dynamometer is a machine used to measure torque and rotational speed (rpm) from which power produced by an engine or electric motor, and relative MPG, can be measured and calculated. Lincvolt has done tests on a couple "chassis" dyno's, where the car is anchored and the drive wheels spin the rollers of the dyno -- from which measurements are taken. Appropriately described as "the treadmill" in the blog; "Under The Hood"