The difference in bumper height between cars and sport utility vehicles leads to costly accident repairs even after low-speed crashes, an insurance group reportedly said.

According to the Associated Press, Ford vehicles had the lowest repair costs in 10mph crash tests because their bumpers were most compatible, while Volvo and DaimlerChrysler vehicles had the highest repair costs.

The institute reportedly wanted to find out what happens when an SUV hit a car from behind and when a car hit an SUV from behind, so it tested five pairs of 2004 and 2005 vehicles, each from the same company: Ford's Taurus sedan and Explorer SUV; Chevrolet's Malibu sedan and TrailBlazer SUV; DaimlerChrysler's Dodge Stratus and Jeep Grand Cherokee; Nissan's Altima sedan and Murano SUV; and Volvo's S40 sedan and XC90 SUV.

"We thought that, at a minimum, automakers should be paying attention to the compatibility of the bumpers across their own fleets," Adrian Lund, the institute's chief operating officer, told the Associated Press, adding that, on some vehicles, such as the Dodge Stratus and the Jeep Grand Cherokee, the bumpers passed each other by.

Ford reportedly had the lowest repair cost of $US1,256 after the Explorer hit the Taurus - $555 in parts and labour for the Taurus and $701 for the Explorer. Ford also had the lowest repair cost of $2,608 when the test was reversed and the Taurus hit the Explorer.

AP said it cost $6,080 to repair the Volvos after the S40 hit the XC90 and $6,129 after the Jeep Grand Cherokee hit the Dodge Stratus. The Nissan vehicles sustained more than $5,000 in damage in both types of crashes, while the Chevrolet vehicles had more than $4,000 in damage in both crashes.

Lund told AP there was far more damage, including broken radiators and major leaks that would require the vehicles to be towed, than most people would expect in a 10 mph crash. He also said it was striking that cars could inflict so much damage on SUVs.

Car bumpers line up reasonably well because federal standards require them to extend from 16 inches to 20 inches from the ground. But no such requirements exist for SUVs, minivans or pickup trucks, so they often have flimsier bumpers or no bumpers at all, Lund said, according to the Associated Press.

AP noted that automakers have promised improvements. Last year, the Alliance of Automobile Manufacturers, a Washington trade group that represents 10 automakers, announced a voluntary agreement to improve compatibility between vehicles by 2009.