The Liberal Democrats called on MPs to intervene on the grounds that the advertising industry's code of practice had failed to stamp out ads including maximum speeds limits that are against the law.
Norman Baker, the party's environment spokesman, said: "The motor trade is not regulating itself properly. The present arrangements encourage the speed limit to be broken, which is bad for road safety and the environment. If the industry cannot behave responsibly, the Government should bring in legislation."
Baker intervened after a complaint from a member of the public about a press ad for an MG 2T 260 V8 car, which used the slogan "experienced players only" and cited its top speed of 155mph.
Government sources said the rules for car ads were kept under constant review. While MPs have warned car makers about their ads, there were no signs that they are preparing a crackdown.
Stephen Timms, the trade and industry minister, told Baker that the Committee of Advertising Practice Code already provided safeguards for motoring advertising. He said it ensured speed should not be portrayed in a way that might encourage motorists to drive irresponsibly. However, it was legitimate to give general information including acceleration and top speed.