Adaptive cruise control (ACC) ... Some ADAS technologies are paired together in some newer vehicles, but this isn't always the case. » MORE: Car safety features: What you need to know.

Adaptive cruise control as of 2013 ranges from $2,500 at the high end to as little as $500. Less costly "partial ACC" only works at speeds of 20 or 25 mph and up, but it's markedly cheaper.

That depends on whether it's old-school cruise control or its modern, adaptive counterpart. ... This is only the case when driving for longer stretches on wide, clear roads, however.