a 2.5 L Ecotec I4 engine or the 3.6 L LFX V6 engine. The 2.8 L Duramax LWN turbodiesel engine was added in 2016, and is a first for its class in the US market. It is also available in three cab configurations: extended cab with a bed, crew cab with a bed, or crew cab with a bed, with four-wheel drive being optional. Sixteen- or 17-inch steel wheels or alloy wheels are available, as well as a decor package for the W/T model that adds a chrome front grille and body-colored door handles and side-view mirrors. Trim levels Base trim level (2015-2020) WT base trim level ("Work Truck") LT midlevel trim and most common Z71, the top trim, includes off-road equipment. ZR2 for off-road performance is the halo model. The base Colorado trim level includes as standard equipment: 16-inch steel wheels, vinyl seating surfaces, an A/M-F/M stereo with auxiliary audio input and a six-speaker audio system, power windows and door locks (no keyless entry), a 2.5 L EcoTec I4 gasoline engine, a six-speed manual transmission (until mid-2019, when the manual transmission was discontinued and a six-speed automatic transmission became standard), carpeted flooring, and a chrome front grille. This model is available exclusively as an extended cab. The W/T includes the same standard equipment as the base Colorado trim level, but has more optional equipment, such as a seven-inch color touch-screen MyLink radio, cloth seating surfaces, keyless entry, 16-inch aluminum-alloy wheels, color-keyed door mirrors, an automatic transmission, and a 3.6 L V6 gasoline engine. It is available as either an extended cab, or as a crew cab with either a short or long box. The LT adds this equipment to the base Colorado and W/T trim levels: 17-inch aluminum-alloy wheels, 3.6 L V6 gasoline engine, automatic transmission, eight-inch color touch-screen MyLink radio, SiriusXM satellite radio, OnStar with 4G LTE Wi-Fi connectivity (later models only), cloth seating surfaces, and keyless entry. Optional equipment includes a 2.8 L Duramax I4 turbodiesel engine, remote start, a rear-view backup camera system, a premium Bose seven-speaker audio system, a GPS navigational radio with MyLink, and chrome exterior accessories. It is available as either an extended cab, or as a crew cab with either a short or long box. The Z71 is the top-of-the-line trim level, and adds this to the LT trim level: unique aluminum-alloy wheels, vinyl and cloth combination seating surfaces, and a black