The Mayor of London, Boris Johnson, is being challenged over congestion charging rules for low-emission vehicles.
In a joint statement, car maker Volvo and What Car? magazine said that the current system "unfairly benefits" hybrid cars, all of which are exempt from charging, while drivers of conventional vehicles with similar levels of emissions must pay £8 per day to enter the capital's congestion charge zone.
The carbon dioxide (CO2) emissions of currently available hybrid-powered cars range from 89 grams per kilometre (g/km) to 219g/km. However, by the end of 2008 there were 13 non-hybrid cars on the market with emissions of less than 105g/km, according to the Society of Motor Manufacturers and Traders.
Volvo's European president, Stuart Kerr, first raised the issue with Johnson at a recent awards ceremony, and reiterated his point in a letter sent to the mayor's office last week.
Adding his backing to the campaign, What Car? editor Steve Fowler said: "With an increasing number of low CO2 vehicles, including diesel hybrids, plug-in hybrids, range extenders and electric vehicles, now is the ideal time to re-open the debate."
Comparisons of the CO2 emissions of all new cars can be made through the Government's Act on CO2 website.
