By RAY MASSEY

Last updated at 00:35 12 February 2008

That sickening - not to mention painful - feeling as your car crunches into a vehicle in front looks like becoming just an expensive memory for drivers.

Volvo has come up with a crash-proof family car which will go on sale in the autumn.

Its secret is a laser-guidance system to spot vehicles in front that are too close or stopping suddenly. When it does, the Volvo will stop of its own accord to avoid a smash.

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The CitySafety system, which kicks in at speeds of up to 20mph and is designed for urban driving, has the potential to prevent half of all rear-end collisions, said Volvo.

A laser sensor built into the windscreen reacts to traffic in front that is either stationary or moving in the same direction.

It scans up to six yards ahead and, sensing the difference in speed between it and a vehicle in front, it makes 50 calculations a second to determine the braking force needed to avoid crashing.

If the driver fails to slow, the system brakes automatically and disables the accelerator.

The system will be standard in the XC60 car, priced from £25,000.

But Jonas Ekmark, of Volvo, said: "It is important to stress that CitySafety does not relieve the driver of the responsibility from maintaining a safe distance."

Safety experts say this and similar technology being developed by other makers will help save more than 125,000 painful and costly whiplash injuries alone each year.

Rear-end collisions make up 29 per cent of all reported car accidents. In more than half, the driver does not brake at all. And 90 per cent of all such collisions are partly due to distracted drivers.

Three-quarters of all collisions happen at speeds up to 19mph.

Volvo said that if the relative speed difference between two vehicles was below 10mph the system can help avoid a collision entirely.

"Between 10mph and 20mph, the focus is on reducing speed as much as possible before impact," said Volvo.

At higher speeds, including on motorways, a separate "adaptive cruise control" system keeps the car safe from traffic in front by braking and accelerating as necessary.

Volvo, Mercedes and Honda will be demonstrating their anti-collision technology at Thatcham, the motor insurance repair research centre, in Berkshire on Tuesday.

A spokesman for the centre said: "It sounds like sci-fi fantasy - cars that can't crash. But the fictional notion is about to become reality."