More than 50% of motorists habitually drive for more than two hours on long motorway journeys without taking a break – and half of those, 25% of all drivers, never stop for a break during motorway journeys lasting four hours or longer.

A survey, conducted by the Institute of Advanced Motorists (IAM), revealed that company car drivers generally continue for longer periods without a break than drivers of privately owned vehicles, while female drivers tend to stop more frequently than their male counterparts.

Motorists who drive cars registered since September last year are more liable to plough on without stopping, as are those who drive a roadster, coupé or convertible. When it comes to age, drivers in the 25-34 age group proved most likely to not stop on a long journey.

The results show that many drivers are either unaware of or are ignoring official advice from the Department for Transport to take a 15-minute break every two hours on a long journey.

The DfT says more than one-fifth of motorway collisions are caused by drivers falling asleep at the wheel and up to one in ten crashes on all of Britain's roads – around 23,000 a year – are also linked to fatigue.