Neither of the two rear seat head rests stay up. Also, they are too low when extended to full height to protect an adult from head injury in a crash or hard stop. Your head hits the rear glass window. I am 5'-9" tall. The head rest does not lock or remain up in any position. Applying very light pressure to the head rest causes it to drop all the way down. This occurs if you sit in the seat and lean your head back. I'm concerned that someone will be injured if these head rests aren't made to engage and stay in the extended positions. The front rests have a lock button that you must push to lower the head rest. The rear ones do not have this feature. This problem has occurred since the vehicle was new. I mentioned it to the dealer but they said that is how they are designed.

- Gilbert, AZ, USA

-Engine gas consumption state 21 MPG Highway, 17 MPG Combined and 15 MPG City. When I started using this vehicle during the first weeks and months the best MPG I could get at the highway is 18.5 MPG with top tier gas such Shell & Chevron during the first 2 years and now Costco brand. Every since I bought it, the gas MPG have gone down around 0.5 MPG. The vehicle feels that it has to use more gas in order to perform. -The motor oil pump at times moves down from the 40 mark to the 20 when idle at traffic light and when it starts moving, it temporarily moves to the 60 mark. -The transmission is an 8 speed automatic. It has issues shifting to first gear, second gear and times 3rd gear. When driving at slow speeds like in traffic jams, mall parking lots or when you slow down at the traffic light and then turns green and you start accelerating again it feels harsh on gearing down and up, like someone rear ended your vehicle. -This truck has the Active Fuel Management (AFM) and it turns on even slower speeds and you feel how the engine and transmission struggle to really gear up and down. Like it never gears and tries to accelerate at a higher gear. Like in manual transmissions when you accelerate on a higher gear than at correct own it takes forever to reach the needed speed. -Even if all 8 pistons are on it feels as if I am running on a smaller engine like a V6 or V4. -The driver car seat feels that move a little like an 1/8 of an inch. -It just feels that something is wrong with motor and transmission.

- El Paso, TX, USA

I've had movement in my drivers seat since the day I've owner the truck. GMC put in a shim kit to address the problem but it's still acting up. They refuse to replace or repair any further. Also my transmission has a horrible shifting problem. When it's cold out or after the first time shifting into gear after sitting a long time, the truck lags to shift into gear then all of a sudden lunges forward or backwards depending on which gear I'm in. I've almost ran through my garage door and side fence and had to slam on the brakes. GMC has looked into the issues but won't resolve them. The last 'repair' made was to change out the transmission fluid. That had helped with the hard shifting while driving but the truck still lunges forward or backwards and lags shifting into gear. I've had to learn to deal with it but anyone else who would drive my truck could seriously hurt themselves or someone else

- Bourbonnais, IL, USA

Constant vibration and or shake at speeds between 60-70 mph. This issue is commonly referred to as the "Chevy shake" this issue has been existing since first purchasing this vehicle. I addressed the concern with the dealership during multiple visits for service. As this was my first full size truck, I wasn't sure what to expect regarding how the vehicle would ride at highway speeds. I was told by the service department that the vehicle was in tolerance in regards to how it rode and the constant vibration. So I excepted this as being the norm and went ahead to add some modifications to my truck. Since the initial complaint the service department has since turned over most of their staff and added people willing to address and acknowledge that my vehicle indeed has this vibration/shake issue. Due to the modifications made they will not address or attempt to correct this issue. Had I pressed the issue in the beginning and not accepted what these so called professionals had told me to be acceptable maybe I wouldn't be in this predicament. My vehicle has also been in for numerous bucket seat issues from sagging and poor seat support. Everything described here is factual as I have all the service records and history with the same GMC dealership and service department in regards to these problems. Long story short, these issues have made long distance trips almost unbearable between the constant shaking and poor seat support.

- Orchard Park, NY, USA

The contact owns a 2016 GMC Sierra 1500. While the vehicle was stationary, the driver's seat became loose and shifted towards the steering wheel after shifting gears. Sunrise Pontiac in memphis, Tennessee was made aware of the failure and updated the firmware in the vehicle. The manufacturer was not made aware of the failure. The failure mileage was approximately 60,000.

- Cordova, TN, USA

Rear bench seat headrests do not stay locked in position when raised. Leaning head back onto headrest causes them to lower which could result in injury to the base of the neck or head during a crash. Also, headrests are too low for full size adults to adequately protect the head/neck from hitting glass rear window during hard stop or crash. Took vehicle to dealership to investigate. Dealer indicated all 2016/2017 model trucks on their lot function this way. Asked to report it here. Rear seat headrests need to be recalled to allow for a locking mechanism to be installed. Rear seat headrest design needs updated to increase back of head/neck protection heights during crash.

- Gilbert, AZ, USA

The driver seat does not go up and down.this is a big safety feature purchased new I can barley see over steering wheel why would you make seatslike this

- Auburndale, FL, USA