Buick Adds a Convertible, Ponders Flagship Model

General Motors Co.'s Buick unit is using the Detroit auto show to debut its first convertible in 25 years. The company also is showing a highly styled concept that could become the brand's flagship sedan.

GM says both four-seaters were developed and styled with global markets in mind.

2016 Buick Cascada

The two-door ragtop Cascada will debut early next year. The car's thermally and acoustically insulated soft top can be lowered in 17 seconds, shrinking trunk space 26% to 9.8 cubic feet. Polelike rollover bars extend out of the tonneau in the event of a crash.

The car is fitted with a Watts Z-link rear suspension designed to improve rear axle centering during turns. Up front is Buick's "HiPer Strut" front suspension, which assigns separate top mounting points for the spring and damper. Buick says the configuration reduces torque steer and better isolates the impact of road bumps to the body structure.

Buick Avenir concept

The car will be powered by a 1.6-liter, 4-cylinder turbocharged engine that makes 200 hp and 206 lb-ft of torque. Output will be delivered to the front wheels through a 6-speed automatic transmission.

Inside, access to the rear seat is aided by a system that automatically powers each front seat forward when its seatback is folded forward. The seats return to their original position when their seatback are flipped back into their upright positions. Telescoping arms present the seatbelts for front-seat occupants.

Buick's Avenir four-passenger concept offers a new grille design, flowing character lines on the side and a radically sculpted boattail rear end in a package that measures 17 feet in length. GM says the car aims for "effortless beauty" and "presence without pretense."

The concept is propelled by a next-generation V-6 engine with stop-start and advanced cylinder deactivation systems. It links to a twin-clutch all-wheel-drive drivetrain through a paddle-shift 9-speed automatic gearbox.

Buick hasn't said whether it will build the Avenir.