Munich  - German carmaker BMW plans to boost the number of frugal, eco-friendly models in its range.

Norbert Reithofer, who is soon to take over as board chairman at the Munich-based company, made the announcement in Leipzig where BMW unveiled the new X1 compact offroader.

The move marks an expansion of BMW's "Efficient Dynamics" strategy which is aimed at cutting the fuel consumption of the range by up to 15 per cent.

At the recent Frankfurt IAA car show BMW showed petrol-electric hybrid versions of the full-size X6 SUV and the 7 series limousine. "In the medium term we want to hybridise the range right down to the 3 series," said Reithofer.

Future BMW technology will include full hybrids in which the combustion engine charges up batteries for electric running along with plug-in versions which use mains power to regularly charge the on-board power packs.

BMW is concentrating on what it calls "Project 1," a "Mega-City-Vehicle" due to be slotted in below the current upmarket range. "By 2015 this family of vehicles will include a battery-electric," said Reithofer.

In the long-term, Reithofer believes combustion engines which burn hydrogen are the way ahead for BMW. "We will remain loyal to this technology," said the BMW chief. The focus was now on designing a better fuel tank to store liquid hydrogen on board. Once the problem had been solved a new generation of demonstration vehicles would emerge.

Although BMW has been successfully experimenting with hydrogen power for more than 20 years the technology has been hampered by bulky fuel tanks and the lack of a hydrogen filing station infrastructure. (dpa)