The Toyota Prius, the world’s most popular hybrid car, emits half as much carbon dioxide as a traditional black cab does. This made it an obvious choice for greentomatocars, an environmentally friendly cab service in London that was launched on 1 March 2006 and was founded by two young ex-City lawyers. Hybrid cars have an electrical engine that takes over from the petrol engine when the car is moving slowly, which eliminates toxic fumes and noise. The company also buys carbon credits to offset unavoidable emissions. Most green services come at a greater cost to consumers. Not so for greentomatocars. In their words: “A radical change in consumer behaviour is needed if society is to arrest climate change. greentomatocars believes that such change is only achievable if environmental businesses do not charge a premium for their goods and services.” For example, a journey from West London to the West End costs GBP 10-11, which is GBP 4 less than than the fare would be in a regular black cab. greentomatocars currently service West London, starting off with a fleet of five cars, and will expand to the rest of London by the end of the summer. Springwise has written about similar initiatives in Boston, New York and L.A., and is not surprised to see this business idea being copied to other traffic-logged cities across the world. Paris? Hong Kong? Sao Paulo?