Road safety officials in the United States are to set to start putting SUVs through test drives rather than relying on a mathematical simulation to determine their roll-over potential.

But US car industry commentators are sceptical that the National Highway Traffic Safety Administration will be able to develop a test which takes into account driver behaviour, road conditions and vehicle characteristics Testing could start as early as September.

Congress passed a bill requiring dynamic rollover testing after the 2000 recall of millions of Firestone tyres of a type involved in deadly rollover accidents with Ford's popular Explorer.