Micro-hybrids set to take off in coming years

One of the biggest contributors to pollution and wasted fuel in urban areas is vehicles sitting in traffic jams with their engines idling. Hybrid vehicles address this problem by automatically shutting engines off when the vehicle is slowing or stopped and then restarting them only when they're needed for acceleration. Unfortunately, the cost premium to add a full hybrid system is still fairly high thanks to the required battery pack and the associated electric motor and transmission system. In Europe, where smaller, more efficient cars already represent a major part of the market, the fuel efficiency benefit of a full hybrid is more limited especially in places like France where diesel engines comprise almost eighty percent of the market. That's where micro-hybrid systems come in. For the relatively small initial cost of what is essentially a heavy duty alternator and 12V battery, Bosch claims that up to five percent improvement in fuel economy is possible. Perhaps more importantly, the emissions during idling are eliminated which can be really helpful with diesel engines.
Of course anyone can manually start and stop their engine at a traffic light. However, regular starters and batteries are not designed to go through that many cycles in their lifetime and are likely to wear out prematurely.

[Source: Wards Auto World]