Stick a couple radar transceivers in the bumper of your $60,000 car, add $2,500 for active cruise control, and you've got an effective means of reducing rear-end collisions. Now, says Continental Automotive Systems, it has a lower-cost optical system, or more precisely a "microoptical laser sensor [using] a highly precise laser runtime measurement [in which] the scene is illuminated by a very short laser pulse." The scene being, say, the car you're about to rear-end.

Continental says the system scans 10 meters (33 feet) ahead and to the sides, and can bring you to a safe stop when you're closing in at 35 kph (22 mph) on a stopped vehicle; at higher speeds, it would mitigate the collision damage. (Radar-based ACC can sense several hundred feet ahead.) The system can brake for the driver, or brake harder if the driver's not braking hard enough. Telematics Update says it will be on a 2008 production vehicle and is sensitive enough to track bicycles and motorcycles as well as cars. Continental described the sensor as affordable but didn't offer pricing guidance.