Is the potential of electric cars being heavily overrated? Daimler thinks so, pointing to surveys that show that, by 2020, 45 percent of all new cars sold will be electric. At the other end of the scale, others say it will be two percent. The short version is that nobody knows.

"For 2025, the market share for Europe is forecast to be between 14 and 53 percent," said Daimler's board member in charge of R&D, Dr Thomas Weber, at a Zero Emissions technical seminar earlier this month.

"A 10 percent share would amount to 20 million vehicles. This is an extremely ambitious target, given the production availability and the lack of infrastructure."

An even bigger problem is energy efficiency compared to a combustion-engine efficiency.

"The ratio of energy in a fuel tank versus a Lithium-Ion battery is getting better but it's not in the same league, without taking into account durability and cost," Daimler strategist Johannes Reisenrath said.

"If we compare the smart CDI and the battery smart and do 150km in both, the comparison is ridiculous. About five litres of diesel is all the energy content the CDI needs, but to do it in the battery vehicle we have to put in an LI battery that weighs 140kg, with a volume of 100 litres. The fuel tank is 5kg, so it is 28 times more efficient in weight and 20 times more efficient in volume.

"Even LI is good, but it's not very close to the fuel tank right now. They will get better over time, but how much better will they get? Will they get 28 times better?"

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