So far, General Motors Corp. is using its Quadrasteer 4-wheel steering (4WS) system exclusively on fullsize trucks, but supplier Delphi Automotive Systems predicts the chassis technology will be applied to more than just long wheelbase vehicles by 2007.

A Delphi official sees Quad-rasteer expanding into minivans within five years, and possibly commercial trucks and cars.

GM is so confident that 4WS is going to be a huge hit with customers that it announced at the Chicago Auto Show in February it would expand use of 4WS to Chevy Silverado/Suburban and GMC Sierra/Yukon XL.

Quadrasteer turns front and rear wheels to improve maneuverability and stability. A fullsize SUV's turning circle tightens from 45 ft. (13.7 m) to 33.9 ft. (10.3m), nearly comparable to that of a compact car.

GM has a two-year exclusivity agreement with Delphi, but after that it's open season. Ford Motor Co. and DaimlerChrysler Corp. say they're interested in 4WS, but won't reveal their development status.

However, Quadrasteer is expensive and will cost “thousands, not hundreds” as an option, says a GM official, who hopes future generations will decrease in cost.