I have noticed this problem for the past 2+ winters on my car. the first time it happened, i was going home from work on a cold winter night. i got the freeway and accelerated to 55 mph. i then set the cruise control (as i normally do in light traffic). i noticed that the car's engine was still revving a lot more than it should. i looked down and noticed that i was doing 70 mph. i immediately stepped on the brake to deactivate the cruise control. i continued to notice this issue all winter. i set the cruise at 40 mph and noticed that it went up by about 20 mph above the setting before it finally stopped accelerating and settled back to the cruise set speed (or close to it). in the warm weather this problem disappears. *tr