On the weekend I was towing a snowmobile trailer (approx 1500 lbs) with my 2010 3.5 litre AWD. Without cruise on - the vehicle would cruise nicely at 110 kph at 1900 RPM. If I turned on cruise, the vehicle would drop to 5th gear and be at 2500 RPM. This was flat road. Bacically I drove without cruise for 3 hours. Any idea why cruise control was having such an issue maintaining speed?