When the GMC Sierra was transformed in 2014 (at the same time as the Chevrolet Silverado), the stylists decided keep the exterior similar to before, but completely change the cabin. Moreover, the chassis and drivetrain were new, which explains why sales have continued to grow over the last several months. This year, the 5.3-litre and 6.2-litre V8 engines are paired with a new 8-speed automatic transmission.