At the New York International Auto Show earlier this month, British engineering company Ricardo unveiled its micro-hybrid system as part of the Taxi '07 exhibit. Ricardo's system would be ideal for taxis used in urban locations such as New York, where the starting and stopping of city traffic would be put to use and charge the motor via regenerative braking. Ricardo estimates that if its system were installed on all the taxis in New York City alone, it would save 10.8 million gallons of gasoline and 105,000 tons of CO2 per year.

The micro-hybrid system replaces the standard alternator with a more efficient electric motor-generator. The system kills the engine when the vehicle idles, reducing fuel consumption and emissions; when the driver steps on the accelerator, the electric motor starts instantly and silently.