I've had 2 Rocs and my first Roc had big failures of the ACC system in 2 consecutive winters, starting up the car at sub-zero temperatures. The selector button flashed and the ride was like a bag of hammers. After the car had warmed up you could turn the ignition off and then back on and the fault was gone. Apparently some sensory failure in each case, not had issue with the current Roc's ACC.