Official figures for 2005 show that on roads with a 30mph limit, typically in built-up areas, half of drivers broke the law. And 21% travelled faster than 35mph.
On 40 mph roads 25% of cars exceeded the limit, with 9% exceeding 45mph.
More than half the cars on motorways and 48% of cars on dual carriageways travelled faster than the speed limit; 19% were travelling faster than 80mph on motorways, and 13% on dual carriageways.
The latest Department for Transport figures show that the proportion of motorists exceeding the speed limit in 2005 changed very little from 2004 although driving in excess of the speed limit remains at a high level on all types of road.