10 most optional extras on a luxury car

For anyone who does lots of motorway driving, traditional cruise control systems just don't hack it. The way that speeds ebb and flow – esecially in the outside lane – mean that dialling-in one velocity and leaving it are very much a pipedream. Adaptive cruise control works by maintaining a gap between you and the car in front, so that when things slow down. your car does the same. But as you've set your desired speed, it won't exceed that either.