Under the proposed system, red dots would flag high-pollution cars, and green dots would signal low-emission vehicles, rated by carbon emissions and fuel consumption. Automotive is the fifth-largest ad category in the U.K. and accounted for 7.5% of ad expenditures in the region last year, according to the World Advertising Research Center quarterly advertising forecast published in connection with the Advertising Association and Nielsen.
Under the proposal, as much as 20% of each car ad would be reserved for information about the vehicle's carbon footprint. The European Commission may also introduce restrictions on the types of images used in car ads. For instance, environmentally unfriendly images of powerful cars traveling at high speed could be outlawed.
The commission has just started an eight-week period of consultation on car advertising, talking to the public as well as media owners and advertisers. So far, only print media is being considered.
Indicating there is a strong push under way to implement the plan, the commission said in a statement: "We hope to have it ready and agreed before the end of the year."
While the proposal might seem harsh by U.S. standards, consider that Europeans already drive more-fuel-efficient cars. According to a report in the Christian Science Monitor quoting the International Energy Agency in Paris, the average light-duty vehicle gets 32.1 miles per gallon on the highway in Europe compared with 21.6 in the U.S.
A similar traffic-light system is already in use in the U.K. for food, flagging products that are high in fat, salt or sugar. The system, which is used on packaging and to determine advertising restrictions, has been controversial because of disagreement over the criteria used. The proposed car-ad rules could provoke similar outrage among automakers.
Honda has pursued an eco-friendly message in its ads but does not welcome the new proposals. "We would much rather have a self-regulated approach than new legislation imposed on us," a spokesman said. "CO2 is not the only discriminator when deciding on a car purchase -- otherwise everyone would be buying hybrids -- and yet we know many buy small diesels due to price considerations. We would welcome a consistent, self-regulated approach that is clear but does not ram information down people's throats."
Chris Arnold, creative partner at London-based ethical-marketing specialist Feel, said: "Consumers are confused. They are looking for simple solutions and guidance. Trust is the biggest problem: The majority of people don't believe car ads' green claims, and honest accreditation would sort out the truth from the blag."
Mr. Arnold said the traffic-light system could work well for auto marketers. "Car companies are coming to realize that no one believes their claims," he said. "If the values are clearly defined, then they will all be competing on a level playing field."
A survey by environmental lobby group Friends of the Earth last year found that 55% of car ads in U.K. national newspapers were for the vehicles that pollute the most -- cars that emit more than 165 grams of carbon dioxide per kilometer. A similar survey two years earlier found that 56.6% of car ads fell into that category, so there has been little voluntary improvement from car brands.