BMW will offer a two-cylinder motorcycle engine and a generator to extend the range of its i3 electric.
Herbert Diess, BMW's head of r&d, said the package will be offered as an option on the i3. He did not say how much it will cost. The option will be available when the i3 goes on sale globally in the fourth quarter.
The i3 has a range on a single electrical charge of 60 to 90 miles. A two-cylinder gasoline engine, derived from a BMW motorcycle, extends the range to about 250 miles on a tank of gasoline, Diess said last week at the Detroit auto show.
The engine is housed in the trunk and connected to a generator that recharges the battery. The engine doesn't transmit mechanical power directly to the wheels.
"I imagine many buyers will order the range extender to cure their range anxiety, discovering later they need it very seldom," Diess said.
He expects the order rate for the option could exceed 50 percent with early buyers, then stabilize at about 20 percent.
He said an electric car fits the needs of urban daily commuters, who could use the gasoline engine for longer trips on the weekend. He added: "For those who plan a daily use of the range extender, probably the i3 is not the right choice, with a plug-in hybrid model being a better suitable solution."