GMC's 2007 Yukon series consists of the half-ton Yukon model, the half- and three-quarter-ton Yukon XL, and a Denali in both Yukon and Yukon XL guises. Both two- and four-wheel drive are available on the Yukon and Yukon XL, and the Denali is an all-wheel-drive model. The base 2WD Yukon is powered by a 295-horsepower, 4.8L V8, while a gas and a FlexFuel 5.3L V8 are optional. The 4WD Yukons are equipped with the FlexFuel V8 only. Both of the 5.3Ls create 320 horsepower, and all of these engines are paired with a four-speed automatic transmission. The Denali matches a 6.2L V8 with variable valve timing that creates 380 horsepower to a six-speed automatic transmission. The basic Yukon comes with a locking rear differential, heated mirrors, dual-zone air conditioning, XM satellite radio, an auto-dimming rearview mirror, and power features throughout the interior. Safety equipment includes a tire pressure monitor, OnStar, stability control, and four-wheel anti-lock disc brakes. First and second row curtain air bags are optional. The Yukon SLT adds rear audio controls, automatic climate control, a CD changer, curtain air bags, and a universal home remote. The Yukon XL is essentially the same as the Yukon, except that its length is stretched by 20 inches, its interior volume is accordingly more spacious, and trailering ability is increased. The 4.8L V8 is not offered with the Yukon XL. At the top of the range is the Denali, which is one of the best equipped SUVs on the market. The only options are enhanced audio systems, a navigation system, a rear entertainment system, a rearview camera, a heated steering wheel, and a sunroof. Some notable optional items on the rest of the Yukon family are a third row of seats, a floor console, fog lamps, and a cargo shade. The Yukon's interior is impressively quiet, especially at highway speeds. The tailgate opens with a touch of a button and, the third row seats tumble forward via another switch. Cabin refinements are some of the best in its segment. Optional 20-inch aluminum rims are available and add a modern look with little deterioration of the ride.