FRANKFURT (Reuters) - From major automakers to niche manufacturers, the race is on to get green cars on the road in the coming years, but one question lingers: after many false starts, are drivers finally ready for them?

Emerging from a savage economic downturn and under increasing regulatory pressure to cut emissions, carmakers rushed to show off a plethora of green shoots at the Frankfurt Motor Show. While manufacturers’ estimates of the size of the market for the cars fluctuated, the need for government support in the early days was a recurring refrain.

France's Renault RENA.PA which unveiled four electric vehicle concepts previewing a new zero-emission product range, at the Frankfurt Auto Show, forecast ten percent of vehicles would be electric globally by 2020.

"We think the potential is beyond but it's going to depend not so much on the technology but on how governments, mayors, presidents and governors are willing to push this technology," Renault Chief Executive Carlos Ghosn, who is also head of Nissan 7201.T said.

He said carmakers had little choice but to make the zero emissions shift, given the high probability that oil prices would go up, and emissions regulations would become tougher.

But the history of the industry’s attempts to go green suggests that affordability is king, after all.

Hybrids, led by Toyota Motor Corp's 7203.T top-selling Prius car, made up less than 2 percent of global sales last year, largely due to the high cost of batteries that leads to a price premium of nearly $5,000 over conventional vehicles.

Electric vehicles and plug-in hybrids are designed to go on battery power alone and are much more expensive than traditional hybrids, which twin battery power and internal combustion engines.

California start-up Tesla Motors’ flagship Roadster sports car goes 240 miles on a single battery charge from a conventional power outlet but it sells for a base price of $109,000.

The company is due to start production of its $49,000 “Model S” family sedan in late 2011 or 2012.

Tesla’s third generation car -- which will benefit from greater volumes and technological refinements -- could be priced below $30,000, chief executive Elon Musk told Reuters.

The company intends to launch this new model in around five years’ time. “It’s intended to be a very mainstream car,” Musk said.

GM’s heavily-touted Chevrolet Volt plug-in hybrid, which is designed to go 40 miles on a single charge, is expected to be marketed at above $40,000.

"At the end of the day, the question for us is what is the cost of the battery to the consumer," Renault and Nissan 7201.T chief Ghosn said.

NO SINGLE APPROACH

PSA Peugeot Citroen expects around 1 in 20 cars sold worldwide to be electric by 2020.

While the industry shares the common goal toward green technology, manufacturers have come up with differing solutions ranging from full electric, plug-in hybrid to efficient conventional powertrains, suggesting one standard solution is unlikely in the near term.

“In the next 10 years I see a European market with many technologies living together. I think it depends very much on the customer, but it will depend also on government and local authority decisions in terms of taxation and regulation,” said Guillaume Gerondeau, Toyota Motor Europe’s director of product planning and marketing.

An estimate endorsed by Ghosn that one in ten cars to be sold in 2020 would be electric is “very optimistic” given the challenge of cutting the costs of batteries, Gerondeau said.

"We don't want to put all our eggs in one basket especially when we don't know the size of the basket," PSA Peugeot Citroen's CEO Philippe Varin said at the show, referring to the electric vehicle segment. "We are not cautious, but balanced." The French manufacturer unveiled its iOn electric car, based on partner Mitsubishi Motors' 7211.T iMiev and is also promoting hybrid technology.

“There is no one fuel to replace gasoline. Each automaker will have to identify which technology they will dedicate their resources to,” said Takehi Uchiyamada, Toyota Motor Corp’s executive vice president in charge of research and development.

“There has to be a technological breakthrough for pure electric vehicles to penetrate the market. We think plug-in hybrid is superior than pure electric vehicles, more practical, more reasonably priced, and close to reality.”

Fisker Automotive Inc, a builder of luxury plug-in hybrids, showcased its first vehicle, a four-door luxury sedan plug-in hybrid called the Karma at the show.

“With fully electric vehicles, consumers are afraid of possibly having to walk home when the batteries run out,” Fisker told Reuters in an interview. “I’m pretty confident that by 2030 that the majority of cars manufactured will be electric,” Musk said. “Certainly by 2050 I would expect that 70-80 percent of the cars on the road are pure electric.”