Many motorists now accept traffic jams as a way of life with more drivers leaving extra time to complete journeys, says a major annual motoring survey.

Drivers believe that more than 70 per cent of motorists speed on motorways, although only 42 per cent admitted exceeding the limits themselves, the survey from the RAC also found.

Almost one in four company car drivers is unaware of tax changes affecting their vehicles from this April, the survey showed.

Based on interviews with nearly 1,800 drivers as well as more than 300 teenagers aged 13-16, the survey showed that congestion affected more than 80 per cent of motorists in some way.

But most drivers preferred to find a way round the congestion rather than switch to alternative transport, with 24 per cent leaving earlier, 22 per cent taking different routes, and 18 per cent changing journey times.

Only 29 per cent were confident to set off on a journey without making any provision for extra time to cope with congestion. This compared with a figure of 41 per cent in the 1997 annual survey.

Asked to rate congestion on a scale of 0 to 3, with 3 indicating "very serious", motorists assessed congestion in London at 2.8 and in other major cities at 2.4

Asked to consider which regular weekly car journey they could give up, 29 per cent would not or could not think of one.

Two in five blamed "too many cars on the road" for the congestion, while 18 per cent blamed roadworks. As many as 10 per cent blamed public transport for the congestion.