Last week, Volvo announced a new prototype of the S60. This prototype uses an F1 style KERS or Kinetic Energy Recovery System to lower its emissions.
Until now, this was mostly used in race cars or super cars like the porsche 918. But now, it is tested in a normal road car.
This system stores the kinetic energy of the car in a flywheel which can store this energy for around 30 minutes. The system can store around 150Wh which is not enough to drive purely electric but it can be used to lower emissions drastically. Certainly in city traffic where you have to start and stop regularly.
Another advantage compared to a conventional hybrid car is that the KERS system is a lot cheaper and a lot lighter. It weighs around five times less than the batteries of a Volvo hybrid car.
So I think that this system would perform very well, certainly in urban area’s. If you drive longer distances, a regular hybrid system would probably still be better.