Does my bumper look big in this? Fatter cars put squeeze on roads

• BMW Mini – 1,683mm; Rover Mini (88-01) – 1,422mm

According to a new report, cars are witnessing an ever- expanding waistline which has become a "major contributory factor" in crashes on minor rural roads, while the chunkier car has also become a hazard in urban streets where residential roads are almost rendered impassable by parked vehicles.

Cars have grown by up to ten inches in width as manufacturers responded to demands for more comfortable interiors and extra safety measures.

BMW's Mini is now 1,683mm wide compared to the diminutive 1,422mm girth of the last Rover Mini sold up until 2001 – an extra ten-and-a-quarter inches. The German firm's 3 Series has expanded by 192mm since 1992 – equivalent to seven-and-a-half inches more.

Accident management firm Accident Exchange says motorists are finding it increasingly difficult to judge the width of their car and advises drivers to exercise caution. The company's claims experts calculate accidents caused by "narrow road blindness" on country lanes leave drivers with bills averaging 2,300 for bodywork repairs.

"The ever-increasing waistline of the modern car is a major contributory factor in crashes on Britain's roads," said claims settlement director Lee Woodley. "Standard lanes on major A roads and motorways have been widened to accommodate this but almost all single carriage roads have remained unchanged since the day they were originally built.

"The problem is also getting worse in urban areas. Cars parked on the road outside people's homes leave an ever-smaller gap for other road users to squeeze by. Drivers are having difficulty gauging the size of their cars, but lack an understanding of narrow lane etiquette and have failed to alter the way they drive."

Rules on lane sizes were changed in 2005 so that major A roads and motorways are now 3.65 metres wide. But Britain's single carriageway B, C and unclassified roads are just 2.43 metres wide on average.

Government traffic statistics show that motorways and A roads account for just 12.9 per cent of Britain's roads network, but carry 64 per cent of traffic. By contrast, minor B, C and unclassified roads make up 87 per cent of the total and carry 37 per cent of all traffic.

Yet they have a disproportionate number of accidents, according to Department for Transport casualty statistics that show 51 per cent of all injuries occur on minor roads, along with 40 per cent of fatalities.

A spokesman for BMW, Gavin Ward, said legislation has forced car makers to fit larger wing mirrors and thicker windscreen and door pillars.

"There is no denying that cars have got bigger. B-pillars are thicker than they used to be and floor structures are more robust. A car today has a lot more inside than it used to do," he said. "People aspire to a bigger car in their price bracket. The Austin 7 was once regarded as a family car but would be seen as a micro car today. There are always going to be pinch points on country lanes, especially if they have overgrown hedges and no white lines. Drivers simply have to be more courteous."

The Society of Motor Manufacturers and Traders said "A segment" city cars had grown in size by 8 per cent – 3in, not including larger wing mirrors – in the ten years since 1999, but MPV people carriers typically shrank by 4 per cent in width as buyers shunned larger gas-guzzling models. Spokesman Jonathan Visscher said motorists downsizing to more fuel-efficient cars typically found themselves at the wheel of a vehicle the same size as the one they were trading in.

"Ten years on, you can get the same level of comfort in a more fuel-efficient car in a segment below," he said.