The Sierra HD and its twin, the Chevrolet Silverado HD, are designed for heavy towing and hauling. The 6.0-liter V8 and 6.6-liter turbodiesel are both mated to a six-speed automatic. The latter employs a heavy-duty transmission made by Allison. A natural gas version of the 6.0-liter V8 is also available. The optional off-road suspension package makes the ride stiffer. Other options include a snow-plow preparation kit and a frame-mounted hitch for fifth-wheel towing. The cab offers a lot of storage space and can easily serve as a mobile office. The top-trim Denali has a luxurious interior. Android Auto and Apple CarPlay capabilities are now part of the easy-to-use infotainment system.