Like conventional cruise control, adaptive or “smart” cruise control maintains a speed set by the driver. It differs in that it also automatically maintains its distance from vehicles in front of it even if they slow down — within limits.

The current systems use radar or laser-based (lidar) sensors mounted in the car’s front bumper or grille to monitor the road ahead. Drivers can establish the following distance between themselves and any cars in front of them by selecting one of several interval settings or, in the case of Mercedes-Benz’s Distronic system, by turning a continuously variable thumbwheel on the dashboard.

If the car ahead slows, the adaptive cruise control is capable of slowing the car, using some combination of throttle control, transmission downshifting and light braking. If the lead car speeds up again or moves to another lane, the adaptive cruise returns its vehicle to the preset speed. If the lead car slows abruptly, adaptive cruise is not equipped to brake as urgently as may be necessary. This remains the driver’s responsibility, but the systems I’ve experienced sound an alarm to indicate that the driver must take action.

Adaptive cruise control currently is found on luxury cars and sport utility vehicles. It made its debut on flagship sedans such as Lexus’ LS 430 (Dynamic Laser Cruise Control) and the Infiniti Q45 (Intelligent Cruise Control) and has begun to spread to more affordable models like the Infiniti EX35, Lexus ES 350 and Volvo S80 and XC70.

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Information for this was taken from’s glossary, written by Joe Wiesenfelder.

Answered by Joe Bruzek on June 5, 2008 in Glossary , How Does That Work? , I'm Just Wondering , What Does This Mean? | Permalink

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