Porsche's tradition of profligate product proliferation has produced a fourth Cayenne model positioned above--yes, above--the already mighty, $90K-plus Cayenne Turbo: the 2006 Cayenne Turbo S. As with other "S" models in the Porsche lineup, the Cayenne Turbo S surpasses its lesser brethren with engine and braking enhancements.

Specifically, the Turbo S's 4.5-liter V-8 gets revised computer controls and larger intercoolers, which allowed Porsche to increase turbo boost pressure to a whopping 27.5 psi. The result is 520 horsepower and 530 lb-ft of torque, allowing the 5192-lb sport-ute to hit 60 mph in just 4.8 seconds on its way to a terminal velocity of 167 mph, making it the fastest production vehicle in the world that can tow a 7700-lb trailer.

Now, those who expect the $111,600 Cayenne Turbo S to look unique in any particular way will be disappointed; apart from the huge, red six-piston front and four-piston rear brake calipers peeking from behind the standard 20-inch wheels--and of course, the "S" badge on the tailgate--there is nothing to set it apart from the plain ol' Cayenne Turbo.