In article ,
Chris B wrote:
On 05/01/2017 21:07, Jeff Layman wrote:

I wonder. I assume you are referring to cutting the engine when stopping
at lights, etc. Sure, it must save fuel, but how much? Well, with a 2l
engine it's around 600ml/hour. But how many cars idle for an hour
during a journey? Also, after a while engine cut-out won't work (at
least, it doesn't in my Jazz because it's designed that way). In
practice, it probably saves considerably less than a gallon a month.


And that at the expense of a beefed up starter mechanism (or early
starter failure) and a much more expensive battery that has to be
"integrated" with the EMC. I have always wondered what the net lifetime
saving of this pseudo green system actually is.

My car's manual tells me the energy (from braking) is stored in a super
capacitor.

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from KT24 in Surrey, England