Renault is displaying four electric cars at the Frankfurt Auto Show, from the ultra-compact Twizy ZE Concept to the more practical Fluence ZE Concept.

The list of automotive brands showing electric or plug-in hybrids at the 2009 Frankfurt Auto Show reads like an auto industry A – Z: Audi, BMW, Citroën, Ford, Hyundai, Mercedes-Benz, Mini, Opel, Peugeot, Renault, Smart, Toyota, Volvo, Volkswagen…

Are plug-in cars the latest fashion for an industry needing to green-up its image? Or is the EV revolution off and running? The New York Times points to the Mercedes S-Class plug-in hybrid as evidence that “no manufacturer could avoid electricity’s surge.” But the paper also presents both sides of the debate on the staying power of electric power for cars.

Despite relatively high costs and limited driving range, plug in advocates believe Frankfurt represents a true shift toward electric driving. “This is not a false dawn," said Paul Scott of Plug In America. “This is the real thing.” The opposing view, as expressed by Willi Diez of the Institute for Automotive Research near Stuttgart, is that “some manufacturers are awakening expectations that they cannot fulfill in a reasonable time frame.”

Audi e-tron

In a bout of schizophrenia, Audi represents pro and con positions at the same time. Johan de Nysschen, president of Audi of America, last week said that no one is going to pay a $15,000 premium for an electric car, and yesterday his company unveiled the e-tron, a high-performance electric sports car which derives its power from four electric motors—two each at the front and rear axles. Renault showed similar ambiguity by releasing a lineup of four separate electric cars, each one more funky and futuristic than the next—while Thierry Koskas, director of Renault’s electric vehicle program, said, “We don’t just want people to buy an electric vehicle because it’s fashionable.”

The direction of oil prices and the ability of political leaders to enforce increasingly stringent carbon emissions laws may ultimately determine whether or not Frankfurt proves to be a turning point for plug-in cars, a flash in the pan, or something in between. But either way, the 2009 Frankfurt Auto Show, which opens to the public on Sept. 17 and runs through Sept. 27, gives a glimpse of what could be—if the environment, economics and technology align. Here’s a list of all 42 plug-in hybrids and electric vehicles—mostly concepts and prototypes—on display in Frankfurt, courtesy of drivesolar.org:

• Audi e-Tron
• BMW Vision EfficientDynamics Plug-in Hybrid
• Brabus Smart Ultimate High Voltage Electric
• Brabus Tesla Roadster Electric
• Citroën Berlingo First Electric
• Citroën REVOLTe Plug-in Hybrid
• EDAG Light Car Electric
• Elektro
• Fisker Karma Plug-in Hybrid
• Fisker Karma-S Plug-in Hybrid
• Ford Focus BEV
• Ford Tourneo Connect BEV
• Fräger Benni Electric
• Hyundai Blue-Will Plug-in Hybrid
• Hyundai i10 Electric
• IndiKar Herpa Trabant
• Johnson Controls Plug-in Hybrid Concept
• Loremo EV
• Mercedes-Benz BlueZero E-Cell Electric
• Mercedes-Benz BlueZero E-Cell Plus Plug-in Hybrid
• Mercedes-Benz Vision S 500 Plug-in Hybrid
• Mini E
• Niemeyer Mini E
• Opel Ampera Plug-in Hybrid
• Peugeot bb1
• Peugeot iOn
• Renault Fluence
• Renault Kangoo
• Renault Twizy
• Renault ZOE
• Reva NXG
• Reva NXR
• Smart 5 x
• Smart Brabus
• Subaru R1e
• Tesla Motors Model S
• Tesla Roadster
• Tesla Roadster Sport
• Toyota FT-EV
• Toyota Prius Plug-In Hybrid
• Volvo V70 Plug-In Hybrid
• Volkswagen e up!