How green is your car? - Toyota's gripes

Toyota has defended the Prius's environmental credentials, pointing to previous studies which concluded that most energy is consumed during the car's use, not during its manufacture and recycling.

'These conclusions are very different from the results of several other scientifically reviewed studies of the life cycle impact of vehicles,' said a Toyota spokesman. 'These studies conclude that the majority of the energy - around 80-85% - comes from the driving stage of the car's life and just 15-20% from the design, manufacture, transport and maintenance. The CNW study shows the percentages to be reversed.'

Toyota is also mystified why two models built in Japan and sold in the US, the Scion xA and xB, get different energy ratings - 46p per mile and 30p per mile respectively. That's despite being engineered with the same processes, built on the same production line, transported and shipped together and distributed through the same dealer network. They also have the same engines and gearboxes, differ in weight by just 20kg and both average around 35mpg.

In response, CNW says: 'Factory costs are higher for more complex cars. That can be the difference between an xA and an xB. More components, more cost.'