The Department for Transport will announce that outdoor will be brought into line with press following a review of its ad guidelines, which ends on Friday (13 June).
Its move comes as the advertising and car industries lobby against plans by the European Union to impose bigger, cigarette-style warnings in all car ads disclosing carbon dioxide emissions and fuel consumption (Campaign, 22 May).
The Government's crackdown follows a threat by the Alliance Against Urban 4x4s to take legal action over the way Britain implemented a 1999 EU directive calling for emissions to be included in all promotional material. The group claims a majority of posters give no information or bury it in the small print.
Sian Berry, the Green Party candidate in last month's London Mayor election, said: "We are delighted to see the guidelines may soon change."