General Motors Corp.’s Saab Automobile unit unveils its new BioPower Hybrid Concept at the Stockholm Motor Show.

Based on a Saab 9-3 convertible running on a combination of pure E100 bioethanol fuel and a pair of electric motors, the concept is billed as the first fossil-free and convertible hybrid electric vehicle (HEV), the auto maker says.

The concept also is the first project developed under a joint investment program between GM’s research and development operations and the Swedish government. Currently, the program consists of a vehicle safety, engine emissions and advanced manufacturing development center in Trollhattan, Sweden, established in cooperation with Swedish universities, research laboratories and parts suppliers.

“Although the exact hybrid application shown in this concept does not currently figure in our production plans, the project has been extremely valuable in helping us further our expertise,” Saab Managing Director Jan Ake Jonsson says of the auto maker’s work with alternative fuel sources.

“It shows how we could develop the sporty performance associated with Saab while using only renewable resources and saving energy overall.”

Conventional power for the BioPower Hybrid comes from an all-aluminum 2L 4-cyl. engine that is turbocharged to make 260 hp and 277 lb.-ft. (375 Nm) of torque. The engine also features Spark Ignited Direct Injection and flex-fuel capability to allow it to run on conventional gasoline.

The all-wheel-drive, full hybrid system adds a 15-kW integrated starter generator, mounted between the engine and 6-speed automatic transmission, along with a 38-kW rear-mounted electric motor that transmits power to the rear wheels for added stability, Saab says.

A 42-cell, 300-volt lithium-ion battery back is mounted under the floor of the trunk without sacrificing cabin or cargo space.

Both powertrains operate in tandem and, when running on E100 bioethanol, produce zero carbon dioxide emissions, the company says.

The hybrid system also features engine stop/start, electric power assist, regenerative braking and electric-only “Zero Mode” capabilities.

“Zero Mode” can be activated by a dash-mounted button and allows the vehicle to operate solely on electric power for up to 12 miles (20 km) at speeds of up to 31 mph (50 km/h).

Saab also says the hybrid 9-3 can accelerate nearly two seconds quicker to 62 mph (100 km/h) than a comparable gasoline-powered 9-3 and has an estimated range of 497 miles (800 km) with a standard 16.4-gallon (62L) fuel tank.