FRANKFURT (Reuters) - BMW BMWG.DE will not mass produce electric cars until 2020 because its current technology is not profitable enough to scale up for volume production, the chief executive said on Thursday.

FILE PHOTO: The plug-in charger for a BMW i3 electric car is pictured during the Auto China 2016 in Beijing, China, April 25, 2016. REUTERS/Jason Lee/File Photo

Munich-based BMW unveiled its first battery electric car in 2013, and has been working on different generations of battery, software and electric motor technology since then.

The i8 Roadster model, due to hit showrooms in May, is equipped with what BMW calls its fourth-generation electric drive technology. Advances in battery raw materials and chemistry has increased its range by 40 percent over the previous version, BMW said.

BMW is working to make electric car technology more modular and scalable to make mass production commercially viable.

“We wanted to wait for the fifth generation to be much more cost competitive,” Chief Executive Harald Krueger told analysts in Munich. “We do not want to scale up with the fourth generation.”

The cost advantage between BMW’s fourth and fifth generation electric vehicle technology was a “two digit number” in percent terms, Krueger said. He did not offer precise figures.

“If you want to win the race, you must be the most cost competitive in the segment, otherwise you cannot scale up the volume,” he said.

BMW is working on a sixth generation of its technology and is investing a three-digit-million euro amount in battery cell research to better understand mass production, the company said.

BMW makes electric cars at 10 plants across the world but has focused mainly on hybrids, which combine combustion engines with battery powered electric motors, rather than vehicles reliant solely on batteries for their power.

BMW said it wanted to add 25 new electrified models by 2025, of which 12 vehicles will be fully battery electric variants.

Thanks to a new production method available from 2020 onwards, BMW will be able to make all its cars with pure electric, hybrid and combustion engined variants.

In 2019 BMW will start making a fully electric Mini at its plant on the outskirts of the British city of Oxford, and will start production of a battery electric version of the X3 offroader in 2020.

BMW is increasing the number of factories where it makes the X3 offroader. This year it will start making the X3 in China and South Africa, in addition to Spartanburg in the United States.

BMW has chosen Contemporary Amperex Technology Co Ltd (CATL) as its partner in China for battery cell production, Krueger said.