The Mercedes-Benz G63 AMG 6x6 is probably one of the more famous ultra-luxury SUVs out there thanks to its wild, six-wheeled design. The 6x6 tips the scales at 8,487 pounds and rockets around with a biturbo 5.5-liter V8 producing 536 horsepower and 560 pound-feet of torque with power delivered to all six wheels through a 7G-TRONIC automatic gearbox. While luxurious, the 6x6 sports a host of off-road goodies.