More than half of experienced drivers would fail the driving test if they were forced to sit it again, according to new experiment.

Auto Express magazine and the Institute of Advanced Motorists (IAM) ran a test with 12 willing volunteers, seven of whom had undergone additional training with the IAM.

Six of these 12 people failed a mini driving test, including just one of the drivers who had not had extra training.

Reliably extrapolating the figures from such a small sample is impossible, but the small-scale study suggests that, since most drivers do not have any further driver training, the nationwide average pass rate would fall well below the 50% recorded here.

Speeding, poor observation and under-use of signals were the most common reasons for failure on the day, under criteria set out by the IAM's volunteers to mimic the driving test.

Steve Fowler, editor-in-chief of Auto Express, said: 'Driving standards has always been a hot topic and the result of our tests shows that too many people just aren't as good at driving as they think they are.

'Although technology is making driving safer than ever, the attitude and ability of the person behind the wheel is the most important element. We always encourage people to take pride in their driving and take additional training if necessary.'

Sarah Sillars, IAM chief executive officer, said: 'The results of our joint experiment were very interesting. It shows that keeping your skills topped up and knowledge of the Highway Code current is crucial in making safer drivers and riders.

'Road skills cannot be allowed to lapse. Keeping your skills current through advanced tuition and other proven methods can only be a benefit to everyone who uses our roads.'