While my wife was driving the car, the electronic parking brake came on causing the car to come to an ubrupt stop on a city street. it did not turn off until my wife turned off the engine, restarted it and shifting through the automatic transmission gears. the car has been at henry brown buick in gilbert, az for over a month and they have not been able to figure out the problem. general motors has refused to do anything further about the problem. this is a life-threatening issue with potential grave consequences if the brake came on again on a highway or in traffic.