4x4s 'twice as likely' to roll in crashes

Large four-wheel-drive vehicles are more likely than other cars to roll over in crashes becuase of their higher centre of gravity, researchers have found.

Their occupants are also more likely to be killed or injured if they hit a roadside safety barrier.

The findings, from a study for the Highways Agency by the Transport Research Laboratory, challenge the perception that the “Chelsea tractors” are always safer to drive.

The researchers studied thousands of crashes in the past decade and found that 4x4s, also known as sports utility vehicles, offered more protection in collisions. Their greater mass and higher riding position mean smaller vehicles tend to come off much worse, especially when a 4x4 overrides their side-impact protection systems. In cars involved in crashes in 2001, at least one occupant was injured in 61 per cent of non-4x4s compared with at least one in 48 per cent of 4x4s.

But the study also found that 4x4s were more vulnerable to turning over after hitting objects such as kerbs or when swerving violently. Injuries tend to be much more severe when vehicles overturn.

Only 2.9 per cent of other cars involved in a crash in 2001 overturned, compared with 6.2 per cent of 4x4s. The gap widens when a crash involves a collision with safety barriers, with 41 per cent of 4x4s overturning compared with 11 per cent of other cars.