When it comes to advances in the mechanisms that control a car, one of the most alluring is four-wheel steering. As the name indicates, this means that all four wheels can respond to a driver's turn of the steering wheel, not just two.
This innovation is part of what John McTague, former science advisor to President Reagan and now head of research for Ford Motor Company, terms ``a major move toward electronic suspensions and steering.''
Overall, he says, ``The automobile is changing more rapidly now than at any time since the 1920s.''
But who'll be the first with dependable all-wheel steering?
The Pontiac Pursuit is a sleek new ``idea car'' which provides a glimpse of what may be coming down the pike in the 1990's. Not only does this model have flush glass, a two-liter, 16-valve turbo-charged engine with intercooler, and tuned port fuel injection, but it also has four-wheel steering.
Other American carmakers are testing the idea; and so are the Europeans and the Japanese.
The Cadillac Allante, a joint effort between Pininfarina of Italy and Cadillac, boasts thousands of dollars in electronics as standard equipment, including early efforts in multiplexing.
The prototype Mazda MX-02, another sleek, aerodynamically styled ``car of tomorrow'' with an array of computer-controlled systems and mechanical components, also includes four-wheel steering.
Tadahiko Takiguchi, head of Mazda's chassis design engineering division, says that the Japanese automaker will use a four-wheel-steering system on the top-line version of a new model that will first be introduced in Japan and then in the United States.
The unique steering system will be combined with an anti-lock braking system, according to the chassis-design engineer.
Honda, too, is driving rapidly toward all-wheel steering and could be the first to move it from the test track to the road.
Mazda's four-wheel-steering system was first tested in Japan in 1983 on the MX-02. Mr. Takiguchi explains that at low- to mid-range speeds, the four-wheel-system steers the rear wheels in the opposite direction of the front wheels.
The result is the ability to park an automobile in a far tighter space because of the reduction of the turning radius of the vehicle. It also reduces the turning circle in U-turns.
At high speeds, however, the rear wheels are turned in the same direction as the front wheels, thus increasing the cornering and straight-ahead stability of the vehicle.
Honda, which began its study of four-wheel steering a decade ago, is touting a mechanical system in which the front- and rear-wheel steer angles are controlled in proportion to the driver's movement of the steering wheel.
On slippery surfaces, this system can reduce the amount of vehicle side-slip, according to Honda engineers. In sharp or reversing turns on narrow roads at low speeds, the front and rear wheels of the car are steered in opposite directions, which reduces the minimum turning radius and makes for better maneuverability. Parking and U-turn maneuvers are simplified as well.
Honda says its four-wheel-steering system is already patented in Japan, the United States, England, West Germany, France, and other major nations around the world.