My wife was sitting at a red light two days ago and when the light turned green the car would not go even with the pedal pressed to the floor. The check engine light started flashing and the car moved at a crawl. After doing a diagnostic with OnStar they reported "Transmission Failure/Powertrain Failure" and to get the car to the dealership within a day. Yesterday the car was towed to my dealership and today we're getting a rental courtesy of GM. My trusted service advisor is in the process of running diagnostics at the dealership and while there's no definite diagnosis yet, he says they will probably need the car for at least a week or so. I have an 09 LS with 28,000 miles on it. Has anyone had any problems of this magnitude or know what could have caused this? We drive mixed (highway/city) through mostly flat terrain here in Buffalo, NY.