The 550-hp SUV: Porsche Cayenne Turbo S

At 500 horsepower, the Cayenne Turbo is one of the fastest sport utility vehicles

on the planet. But it isn't the most powerful or the quickest to 60 - that title goes to Mercedes-Benz's ultimate ML, the AMG-ified ML63 AMG, which out-muscles the spicy Porsche by just 3 horsepower and bests the Cayenne Turbo to 60 mph by 0.1 s. Porsche is, however, fighting back with a little extra, the Turbo S.

The Cayenne Turbo S puts the hammer down, providing an additional 50 horsepower and a whopping 88 lb-ft of torque, and has fattened that torque curve in many areas to provide brutal, Mercedes-smiting acceleration. The gains were made thanks to a reprogrammed ECU and a new sport exhaust system with better airflow. Porsche says that the Turbo S can accelerate to 60 mph in 4.8 seconds, down from 5.1 seconds with the regular Turbo, and will continue to accelerate until 174

mph is reached, 3 mph higher than the standard SUV. And these upgrades come at no cost to fuel economy.

This being the ultimate Cayenne, Porsche has opted to add a few special touches. The Turbo S will be available with standard 21-inch alloy wheels with a similar spoke pattern to the high-performance GTS, bespoke Lava Gray paint and two unique two-toned interior schemes. For 2009, Porsche is also making its PCCB carbon-ceramic brakes available. The system, which features 16.1-inch diameter front discs with telltale six-piston yellow calipers, will be available on S, GTS, Turbo and Turbo S models that have 20-inch wheels and larger.

The Cayenne Turbo S, with its body-colored fender flares and grille trim, will go on sale in Europe this August, and will retail for 111,400 euros.