Essentially mechanically identical to Chevrolet's Suburban, the 2009 GMC Yukon XL rides on General Motors' full-size SUV platform. Half-ton 1500 and heavy-duty 2500-series models are available, with rear- or four-wheel drive. The standard engine size is a 5.3-liter V8, available in either gasoline or flex-fuel versions (the latter can operate on E85), with 6.0-liter V8s optional. Or, buyers may step all the way up to an extravagant Yukon Denali with its class-leading 403-horsepower 6.2-liter V8, all-wheel drive and upgraded level of features and luxury appointments.