When idling or when you cold start the car it tends to have a slight shake/tremble feel all throughout the car even passengers felt it also when accelerating slowly and you hit 15 mph car tends to shift hard into 2nd gear
On august 5, 2019, i was travelling down a two lane road @ 35-40 mph and with a loud clunk from the rear of the car, the rear wheels locked up. i went into a skid and the front of the car swerved back and forth across both lanes. i was able to keep the car under on the road as i applied the brakes and steered into the skid as the front of the car swerved back and forth. fortunately, an oncoming driver was able to stop his car in time to avoid a head-on when he saw me swerve into his lane. i called the dealer, who sent a tow truck. the service manager looked at the car the next day and confirmed the differential was bad--all kinds of metal chunks came out with the oil when they drained it. he told me that the interior of the differential had pretty much self-destructed. the car was within its powertrain warranty, so the service manager said the dealer would replace the differential. almost two months later, the dealer hasn't located a replacement differential. this car is a cadillac v-sport, a performance-oriented model with an electronic limited slip differential. during the years this model was in production, general motors made less than 1,000 per year, and i believe that perhaps the differential was a special type for the v-sport, although i am not sure. i do know of others having this exact same problem--they have reported the problem on a cadillac v-sport user's group found at cadillacforums.com. the attached pictures show the skid marks made by the rear wheels and where the front of the car ended up. the car on the side of the road is mine, where some passersby pushed the car.
The vehicle accelerated on its own when it was in park, with the emergency brake engaged, and the engine was turned off. home security camera captured the entire incident on film. would be happy to provide the nhtsa with the footage.