Around one in four drivers (23 per cent) admitted their vehicles had a fault which rendered them illegal and 14 per cent said their cars were in need of urgent repair, the Britannia Rescue survey showed.
The most common defects were bald tyres but other common problems included faulty brakes, broken wipers, broken or missing wing mirrors and defective brake lights.
Some 18 per cent of motorists have driven a car without a valid Ministry of Transport (MoT) certificate.
Two-thirds of these MoT offenders said they did so unknowingly because they had forgotten to check the renewal date on the certificate but a third said they did know and drove their cars anyway.
As many as 21 per cent of drivers did not realise they were breaking the law by driving a vehicle that had a defective brake light and 19 per cent were unaware that it was an offence to drive with faulty brakes.
Britannia Rescue managing director Peter Horton said: “At a time when money is tight and fuel prices are on the increase, motorists are looking to save cash where they can.
“But sacrificing car maintenance is a false economy.”
The survey involved 2,085 motorists.