Originally Posted by BavarianFanatic
I doubt very much the regenerative braking recovery will come anywhere near compensating for the battery mass penalty. Unless of course you drive downhill all the time.
If you take into account that mass is only important (in discussion of fuel economy) during acceleration you can come to some rudimentary conclusions based on the formula for KE.
To accelerate the additional 305lb of the AH3 to 40MPH, it would require ~280,000 J of energy. Stopping the 3860 lb car from 40 MPH (factoring in an efficiency of roughly 85% for the battery and inverters, which is close) would produce 3,084,000 J of energy. If you ask me, that's a pretty substancial gain. That energy can then be used to assist the ICE, allowing it to run at a more efficient speed and use less gas.
For the assertion of only being useful on hills, it is true that the benefit is even larger there because normal cars simply lose all the energy put into climbing, hybrids can recapture much of that energy. But that doesn't mean it isn't still successful in stop and go.