2012 Mercedes-Benz SLS AMG Roadster Testing

MONTVALE, New Jersey — Mercedes-Benz and AMG development engineers are putting the final test miles on the all-new 2012 Mercedes-Benz SLS AMG Roadster, the soft-top sibling of the SLS AMG coupe. The Roadster makes its public debut in September at the 2011 Frankfurt Auto Show and goes on sale in the U.S. toward the end of this year.

The soft-top edition of the SLS AMG swaps the coupe's fixed roof and signature gullwing doors for a folding canvas roof and conventional doors. It gets additional structural bracing front and rear, as well as a reinforcing crossmember behind the seats that also supports the fixed rollover protection system.

Engineers are conducting a battery of tests on public roads; the preproduction prototypes wear minimal disguise, but carry no official markings, logos or model designations — just strips of black adhesive foil at the front and rear and along the body sides.

In fact, the SLS AMG Coupe and Roadster were developed in parallel, but engineers have spent additional hours testing some of the Roadster's unique features, including its three-layer fabric soft top and folding mechanism, which is constructed of magnesium, steel and aluminum to save weight.

The power-operated soft top, which stows behind the seats, can be raised or lowered automatically in about 11 seconds at speeds up to 31 mph, and is designed for speeds up to the car's electronically governed maximum of 197 mph.

The SLS AMG Roadster prototypes have been put through their paces on country roads and long-distance highways and in city traffic, in locations from Affalterbach, Germany, to Laredo, Texas. The cars also have undergone endurance testing off-road, as well as completing countless high-speed loops on the Nordschliefe at the Nurburgring.

Inside Line says: Trust Mercedes to make sure this car is as close to perfect as possible before it sees the light of day at the IAA.