Just what America needs - a car even bigger than the Hummer

It may not be long before drivers of the Hummer - the steroid-laden sports utility vehicle favoured by the likes of Arnold Schwarzenegger - get a fright when they look in their rear-view mirrors.

It may not be long before drivers of the Hummer - the steroid-laden sports utility vehicle favoured by the likes of Arnold Schwarzenegger - get a fright when they look in their rear-view mirrors.

Trailing them will be a set of wheels even bigger, greedier and more eye-catching than their own.

The US Army and the Chicago manufacturer International Truck and Engine Corporation are jointly developing a replacement for the venerable Humvee troop transporter, from which the Hummer was derived.

Last week, prototypes of the so-called "Smart Truck 3" were displayed at a trade show in Las Vegas. The army also wants the vehicles to be marketed to other customers such as government agencies or regular Joes who only feel right using a stepladder to get behind thewheel.

The commercial version would not have the electronics designed to detect anthrax, the Kevlar armouring on the underside, the night-vision cameras and the 25-inch LCD touch-screen computer monitors. But it would be just as big.

The Smart Truck would weigh in at no less than 8,000lb, compared to nearly 5,000lb for the second generation Hummer, the H2. It would be about 3in higher than the Hummer and 4ft longer, but its fuel consumption would be lower.

However, the era of bigger-is-always-better may have passed, even in size-obsessed America. Sales of the Hummer in the first 10 months of this year were down by a fifth compared to 2003.