How green is your car? - Introduction

Think buying a hybrid car means you're doing your bit to save the planet? You're wrong - or so a new American study claims.

The three-year investigation by Oregon-based CNW Marketing Research measures the environmental impact of cars from the time they're built until the moment they're scrapped. The results have revealed the dilemma faced by buyers looking for cars that are kinder to the environment, with supposedly 'green' cars finishing well down its final league table.

The new analysis extends from the car's fuel consumption and CO2 emissions to the energy used in its design and production, both in car assembly plants and by suppliers of parts and sub-assemblies. Researchers also looked at the energy consumed in transporting the cars to dealers, as well as in maintaining, servicing and scrapping them.

The total amount is called the car's 'dust to dust' energy use. Previous studies have concluded that about 80% of the total energy used in a car's lifetime is consumed when it is being driven and the remaining 20% during its manufacture and recycling. CNW's report has turned that theory on its head, with a number of cars with supposedly good fuel economy and low CO2 emissions at the bottom of its results table.

Naturally, car makers disagree with the report. Ford, Toyota and Volvo say CNW has put too much emphasis on the manufacturing process and not enough on driving.

Read on to find out more.