Opel/Vauxhall plans to unveil two new cars at the Frankfurt auto show in September and announces what it calls the surprise debut of an experimental car.

The Astra GTC and Zafira Tourer will make their world debuts at the show Sept. 15-25, following the media reveal on Sept. 13.

But the General Motors subsidiary says its headline story will be an experimental vehicle that explores a new interpretation of “driving fun.”

It says it will release more details later but is confident the car will wow the media and public with its level of innovation.

Besides the two unveils, the two brands will show a series-production Ampera electric car soon to appear in European showrooms.

Opel/Vauxhall’s fuel-efficient vehicles with conventional powertrains also will be represented by a series of seven low-emissions ecoFLEX models from a variety of model lines.

At launch, the new Astra GTC coupe will have a range of gasoline and diesel engines with outputs of between 120 hp and 180 hp available to order before the car hits U.K. showrooms later this year.

The new Zafira Tourer MPV has a completely redesigned Flex7 seating system and fine driving dynamics to complement its range of new engines.

The Zafira Tourer will go on sale in early 2012.

Opel/Vauxhall says its Ampera, which is a cousin to the Chevrolet Volt, is the first EV from a European auto maker to eliminate range anxiety.

A 16-kWh lithium-ion battery pack feeds the 150-hp electric-drive unit.

Depending on driving technique, terrain and temperature, it delivers 25 to 50 miles (50 to 80 km) of electric operation, ample for a vast majority of U.K. commutes, with zero emissions.

But Opel/Vauxhall says a range extender allows the Ampera to travel for more than 300 miles (483 km) on electric power.

Opel/Vauxhall says it is raising the bar even higher with the launch of seven new ecoFLEX derivatives across four ranges: the Agila 1.0L gasoline (109 g/km of carbon dioxide), Meriva 1.3L CDTi (109 g/km), Astra 1.7L CDTi (99 g/km), Insignia 1.4L Turbo gasoline (134 g/km) and Insignia 2.0L CDTi (115 g/km), as well as ecoFLEX versions of the Astra GTC and Zafira Tourer.