Luxury Crossover Comparison: 2009 Audi Q5 3.2FSI, 2009 Mercedes-Benz GLK350, 2009 Volvo XC60 T6

Techtonics: Compact Crossovers
Don Sherman Three ways to do the twist. Each of these compact crossovers employs a six-cylinder engine to power all four wheels in a slightly different manner. Audi and Mercedes-Benz agree on the 90-degree V-6 format with variable intake and exhaust valve timing. The two German engines achieve about the same peak power (270 hp for Audi, 268 hp for Mercedes), with the larger Mercedes engine generating a bit more torque. To manipulate airflow into the combustion chambers, Audi uses variable valve lift while Mercedes favors adjustable port flaps. Volvo lines its cylinders in a row and positions the engine transversely in the XC60's chassis. A twin-scroll turbo boosts the 3.0-liter six to 281 hp and 295 lb-ft of torque to trump the Germans' output. The Audi Quattro and the Mercedes 4Matic all-wheel-drive systems both employ a rear-biased torque split (40/60 front/rear in the Audi, 45/55 in the Benz). The Q5's Torsen limited-slip center differential is capable of routing a maximum of 65 percent of the available torque to the front wheels but no more than 85 percent to the rear wheels. Mercedes uses a multiplate clutch in the center differential to keep one axle driving when the other loses its footing. In the Volvo XC60, drive to the front wheels is direct. A Haldex coupling adds rear propulsion in response to commands from a control computer. All three crossovers use momentary brake applications to curb wheel spin.