Extreme lag/delay- harsh engagement when shifting from park to reverse. Its like you are backing into something? when cruising 28-32 mph and releasing accelerator(as if you were coasting into a turn) when slowing the vehicle seems to shift up and lunge entering the turn. Clunks and shifts hard when cruising normally when you have to release the gas pedal and slightly reaccelerate, causing the driver to hesitate. Vehicle shutters and hard accel 10X worse when towing a 7000 # trailer (truck is rated over 12,000 lbs. Towing).

- Sequim, WA, USA

The contact owns a 2015 GMC Sierra 1500. While driving various speeds, the transmission vibrated and caused a hesitation when the gears shifted without warning. The vehicle was taken to the dealer and repaired; however, the failure recurred several times. The manufacturer was made aware of the failure. The failure mileage was 50.

- Spokane, WA, USA

First of all the headlights are very dim and at night cannot see nothing.dealer said it is what is.very bad !! also my Sierra on window sticker states comes with all terrain tires it does not have all terrain tires. They are 265/65/R18 Goodyear Wrangler sra.I worked for Goodyear and those tires are all season !!! not all terrain as specified on window sticker !! I talked to dealer and called customer service at GM they never call back and they said those are the right tires.they are not according to my attorney who states the window sticker is totally incorrect and is fraudulent check your tires and window stickers and compare and look on goodyears website you will see.also my transmission clunks and knocks and shifts incorrectly dealer states its normal I spend 40K on a new truck and all I have are problems and GM does nothing. It downshifts horrible what can I do"?"

- Los Angeles, CA, USA

Delayed engagement in drive, transmission clunks, RPM flares and truck quits moving unexpectedly. Shudder at 3- 50 mph, vibrates steering wheel and leaves an uneasy feeling the truck is going to quit moving.

- Montgomery, AL, USA

Purchased vehicle with just over 9,000 miles on it. Noticed excessive vibration at highway speeds. At just over 12,000 miles driveshaft suffered catastrophic failure at low speed in a residential area. Failure occurred on a wet road under moderate acceleration at around 10-15 mph. Driveshaft literally ripped into two pieces.

- Castle Rock, CO, USA

The contact owns a 2015 GMC Sierra 1500. While driving 60 mph, the vehicle began to decelerate and the engine warning light illuminated. The vehicle was towed to a dealer where it was diagnosed that a gear cylinder fractured. The vehicle was repaired, but was unable to be driven. The manufacturer was not notified of the failure. The failure mileage was approximately 4,000.

- Fenton, MO, USA

Brought in my 2015 GMC 1500 Sierra truck in for vibrations issues at high speed of 70-75 mph. After 4 attempts GMC Corp refuses to admit that there is a safety issues in driving this vehicle at a normal rate. They continue to remove and replace the tires. I have never owned a vehicle before that such vibration is felt in the cabin of the truck, passenger seat, foot petal, etc.that is so uncomfortable, that my wife refuse to drive in the truck due to its safety. GMC will not acknowledge any of these complaints but will say everything is of specs. Like others this is the worse vehicle I have ever purchased. Found more complaints like this has been filed, but same result, GMC will do nothing.

- Waveland, MS, USA

Truck starts to vibrate at 60 mph and gets worse the faster you go.

- El Monte, CA, USA

On two separate occasions my truck has acted like it is in neutral while driving. The drive system disengages and the engine just revs. Once this happened while driving down the road, the other when the truck was stuck in snow. When it was stuck it disabled the 4WD system completely, rendering the vehicle stranded.

- Elkview, WV, USA

Headlights are very poor (when wet road or in town) cannot tell they burning...I have 20/20 vision......on slow down does not down shift....cannot accelerate....the starter hangs up on start as if does not fire or no fuel pump

- Rocky Mount, NC, USA

The transmission seems to slip or hesitate at takeoff. The running lights are too dim to see down the road.

- Vancleave, MS, USA

Driving my new 2015 GMC $52,000 GMC Sierra, I noticed a distinct slipping/hesitation/general roughness when accelerating from a dead stop. The truck seemed to either have a transmission or engine problem. Took it back to dealership for them to check, and they indicated that this was "normal" and it was just the "cylinder deactivation" feature performing as designed. I explained to them that cylinder deactivation only typically happens at highway speeds and especially not from a stand still. They stuck by their story and again stated this was normal. My son came to see me and drove my new truck. Of course the truck hesitated and slipped from a dead start. "what's wrong with your new truck dad?" he asked. I told him it was 'normal and he just rolled his eyes. This is not normal for every Sierra that GMC makes with the 5.3 engine and 6 speed transmission would do this. I have read on numerous message boards and websites where this is an issue and GM needs to fix the problem. Also, the headlights are extremely dim and are barely usable. As others have stated, I can only see maybe 20-30 feet in front of me and not very bright at that.

- Eatonton, GA, USA

I had made a complaint to chapdelaine Buick- GMC that my brand new truck did not seem to go into four wheel drive. I was told to bring the truck to the dealership and they would check it for me. I was told by the service department that the truck worked just fine in four wheel drive. I then noticed that the truck seem to shift very rough and I called the service department and told them that something had to be wrong. The service department asked me to bring the truck back down to them the next day and they would take it for a test drive. While I was driving the truck to the dealership it shifted from drive into neutral.I coasted to a stop put the vehicle into park shut off and restarted the engine and then shifted back into drive and tried to drive again. This time the vehicle service engine light came on and the vehicle stayed in low gear and would not shift into a higher gear. The best speed I could make was 10 mph. I stopped the vehicle and restarted two more times. On the second try the vehicle did go into drive. I made it to the dealership and they took it for a test drive and upon their return gave me a loaner vehicle. They had to rebuild the transmission on my brand new truck which took about three days. Thankfully this event took place on a back road with little traffic. If it had happened on a busy road an accident might have occurred.

- Ashby , MA, USA