[bondvagabond]

Originally Posted by Ecky

Simple adding an electric motor to a conventional ICE system doesn't make it more efficient. Cars like the Prius gain efficiency by allowing the ICE to be more efficient by:

-Running Atkinson Cycle, which has greater efficiency but considerably less torque at a given displacement, especially at lower RPM
-Allowing the gas engine to be downsized below what would otherwise be acceptable in an ICE-only car
-Allowing the engine to shut off when not needed, and start back up unobtrusively

Rather than helping your fuel economy, adding such a hybrid system will probably hurt it. Converting mechanical energy to electrical and then back to mechanical is lossy. Running an ICE at lower loads is less efficient, so taking load off of an ICE is counter-intuitive if you're looking to save fuel. Hybrid assist allows a smaller displacement ICE to cruise at higher load, saving fuel. Plus, you're adding weight to the vehicle, which costs energy to accelerate. The only area that might save you some fuel is that you can drive around using grid electricity until the battery is depleted.

Adding an electric motor will definitely give you more power, but unless you do some serious changes to the ICE, you're not going to see economy gains.

Totally agree, but if you did grid tie for the electric it might make sense, One of those monster garage shows did a front wheel drive Mini Cooper with 2x100+ Hp snow mobile engines mounted in back driving the rear wheels. Since electric motors don't really need transmissions you could get by with a simple chain drive setup like them.