A shock new study shows...

A shock new study shows that driving at 20mph instead of 30mph actually pumps out more CO2. Research carried out by the AA has revealed that slowing traffic down can boost carbon dioxide levels by as much as 10 per cent.

And the motoring organisation is warning local authorities that well intentioned safety schemes could backfire in environmental terms. The hike in CO2 is due to the fact that cars aren’t at their most efficient when running very slowly.

The AA‘s investigation claims a petrol model on a 20mph street could emit nearly one tonne of extra CO2 per mile. “Transч­port planners have minimal official guidance on the environmental impч­act of 20mph speed limits,” explained AA president Edmund King. “It would be a bitter irony if local authorities are found guilty of pumping up emissions through the indiscriminate use of these restrictions.”