Consider this truck-based SUV a more luxurious Chevrolet Suburban. Unlike the shorter Yukon, the third-row seat in the XL is a bit roomier, and there is plenty of cargo room when that row is raised. Power comes from a 5.3-liter V8 and six-speed automatic that returns 16 mpg and is just this side of sluggish. The Magnetic Ride Control suspension on the Denali improves ride comfort and handling response. The 6.2-liter engine is a meaningful upgrade but can't make this big barge quick. Properly equipped, the XL can tow 8,500 pounds, its only advantage over a car-based SUV. Changes for 2016 include available lane-keeping assist and Apple CarPlay capability. Reliability has been much below average.