General Motors may allow buyers of its Chevy Volt electric car to rent the vehicle's battery as a way of pricing the vehicle at a comparable level to a traditional, petrol-driven family saloon.
The Volt is emerging as one of the most crucial vehicles in GM's history. Failure would be a deep embarrassment after the fanfare surrounding its development. But success could propel GM past Toyota as a pioneer in alternative energy vehicles. GM has assigned 150 engineers to the project.
The Detroit carmaker aims to launch the Volt by 2010. The battery would give a range of 40 miles and maintain full performance for at least 10 years. It would be recharged either by the car's small combustion engine or from a normal electrical point.
Battery rentals would help fulfil GM's goal of giving the Volt a wider appeal than the petrol-electric hybrid vehicles now on the road. Noting that the Volt will be marketed under GM's global, mass-market Chevrolet brand, Frank Weber, the carmaker's chief engineer, said that it "needs to be affordable to the buyer of a normal mid-sized car".
Bob Lutz, GM's vice-chairman, said the Volt would be produced in both left- and right-hand drive versions. GM has so far shown a concept saloon model, but plans to unveil a second design at the Frankfurt car show next month. "We see it being sold round the world," said Mr Lutz.
GM's confidence contrasts with reports that Toyota has delayed the launch of new hybrid models because of concerns about battery safety.
Justin Ward, a Toyota engineer, told a research conference last week that lithium-ion battery technology "hasn't proven that it's ready for the automotive market yet".
The two companies are pursuing different lithium-ion chemistries. Toyota uses nickel cobalt aluminium oxide, while GM has turned to a newer nanophosphate technology.
Ric Fulop, co-founder of A123Systems, one of three companies developing the Volt's battery pack, said a big challenge was to maintain temperatures throughout the battery once it was in a vehicle.
GM's goal is to price the Volt, excluding battery, at about the same level as its Chevrolet Malibu saloon.
Mr Weber estimates that an average Volt owner would spend about $25 (€18.53)a month on petrol, against $145 (€107.50) for an equivalent petrol model. The difference could be used on battery rental payments, giving a similar total cost.