Test-Driving Porsche 911 Turbo Cabriolet: 480 Horsepower

From speed to sound system, everything you want to know about the new Porsche.

ByABC News
January 8, 2009, 12:17 AM

Sept. 10 -- STUTTGART, Germany -- Dawn is breaking as I turn onto the autobahn south of Stuttgart behind the wheel of Porsche's new 911 Turbo Cabriolet, which has just gone on sale in the United States.

I hit the gas, and in less than four seconds, I've blasted from standstill to more than 62 mph -- something you'd normally need a sports motorcycle to do.

In about 13 seconds, I'm racing at over 125 mph -- and then I realize I'm only in fourth gear. A few seconds later, I'm briefly cruising at about 170 mph in fifth gear, with plenty of room to go before reaching the max speed of 192 mph. However, one emotion prevents me from taking the car up to the sixth and highest gear: fear.

I'm too scared to put the Porsche into top gear, even though I'm on a half-mile stretch of straight autobahn and in complete control of the car. But then again, I'm going as fast as a jet taking off from a runway.

As I grip the steering wheel, passing more cars than I'd expected to meet at daybreak, I'm concentrating too hard to think about the automated gadgetry that makes this high-thrill driving possible.

The new Cabriolet Turbo is not merely a convertible version of the 911 coupe, some hardtop with the roof sawed off. Added are electronic sensors and an aerodynamic design that couple better handling with power.

As I steam along, the electronics are hard at work. The car feels as if it were gripped to the pavement by train tracks, giving me the freedom to choose the trajectory I want, when I want.

At 8:30 a.m., when traffic becomes too thick for (reasonably) safe high-speed driving, I slow down to 125 mph.

Its time to listen to some music. I wonder, though, how this will be possible at such a high speed. Already, its very loud, and with a passenger in tow, it's difficult to talk without shouting.

To get you out of trouble, the Porsche's computer and sensor systems perform thousands of computing tasks in milliseconds.

The traction-management system prevents the tires from skidding. A stability-management system distributes torque between the all-wheel-drive Cabriolet’s front and rear axles. If the wheels in the back begin to lose traction on a wet surface, the system feeds more torque and power to the front axle.

For speed freaks who want to experience what Porsche calls the “lateral dynamics on the race track� – i.e., skidding -- the stability-control system can be deactivated with a button on the dashboard. However, even then, the traction control is reactivated as soon as the brake is stepped on.