>Sounds good. I suppose though you have to brake a lot to build up potential, thus needing to replace the brakes more often, with the power it requires to make new brakes. Ain't no such thing as a free lunch :-)

Ah just look it up - it doesn't use brakes for breaking as long as it can use the momentum to turn the electric motor, using it as a generator. So it's not the heat that's transformed, it's the dynamic energy which is _not_ transformed into heat, but back into electricity. So it's still not a free lunch (had to use some gasoline at some point to produce that momentum); it's rather the part of the lunch which was previously thrown away.