DETROIT – Anyone wielding a chain saw can lop weight off a car, says Dieter Zetsche, chairman of Daimler and head of its Mercedes-Benz luxury division. “It might even be fun.”

But Mercedes engineers worked more deliberately in trimming 275 lbs. (124 kg) from the all-new ’13 SL550 that goes on sale in the U.S. this spring.

“As every athlete knows, decreased weight means increased agility,” Zetsche says at the debut of the luxury hardtop-convertible roadster here at the North American International Auto Show. “For automotive athletes, we might add: Saving pounds means saving gallons.”

SL stands for “super light,” he says of the car he touts as an “automotive icon.”

Its roots are in racing; Mercedes introduced the first street-legal SL-Class 60 years ago in America at the urging of Max Hoffman, a U.S. importer.

Much of the new SL-Class is aluminum, including a highly rigid body shell, “which, in my humble opinion, in itself is an automotive artwork,” Zetsche says.

While the new car, at 3,947 lbs. (1,790 kg) is lighter than its predecessor, it also is more powerful. That is because of a new, direct-injection V-8 engine producing 429 hp. It is smaller, more powerful by 12% and more fuel-efficient. Torque power is increased 32%, to 516 lb.-ft. (699 Nm).

The new twin-turbo engine, featuring a stop/start function, is mated to a 7-speed transmission.

“It is two cars rolled in one,” Zetsche says. “A breathtaking sports roadster and a luxurious coupe. But don’t worry, we won’t use that as an excuse to double the price.”

New on the SL is a transparent roof that switches between light and dark at the push of a button. In the light setting, it is virtually transparent, offering an open-air effect.

This is the sixth generation of the car. Each iteration has lasted on average about 11.5 years, Zetsche says. ”Each generation has set the benchmarks for its time, in both design and technology.”

Pricing is pending on the ’13 SL550. The price of the ’12 model is $104,525 for the SL550, $141,315 for the SL63 AMG.

sfinlay@wardsauto.com