[B Knotts]

Hybrids only save fuel under particular circumstances, where there is a lot of idling.

I think that they are going to have to rely more and more on diesel to meet this regulation.

[mamelukesabre]

I disagree. A hybrid powertrain allows a smaller internal combustion engine for the same peak power output. That alone translates to a superior fuel economy figure.

Personally, I think the CV transmission is the next big thing. This transmission keeps an engine at constant RPMs. So an engine design can be optimized for only one speed. The use of a CV transmission with a small diesel engine and lightweight automobile construction should give us some amazing fuel economy figures. The next step after that would be hybrid tech. But there’s some research work to do before a compression ignition engine can be used in a hybrid powertrain.

[steve86]

Hybrids only save fuel under particular circumstances, where there is a lot of idling

Well, idling, start and stop and low-load usage.