"dennis@home" gurgled happily, sounding
much like they were saying:

And some modern BMWs use regenerative braking via the alternator. So
you don't even need a hybrid for that...

What do they do with the energy?
The battery should be charged by the alternator within a few seconds of
starting the engine so I doubt if it could store the energy generated.
Its probably just some marketing man telling porkies.

They run the alternator light under computer control to help save a
weensy drip of fuel. (Same with the oil pump, ffs... If that isn't a
recipe for disaster, what is?)

Then there's the stop-start of the engine in traffic, so greater battery
consumption due to more regular starting.