FRANKFURT -- BMW is "not at all concerned" by Volkswagen taking a stake in carbon fiber supplier SGL Group, BMW's joint venture partner.
"We are open. Another automaker who helps to lift volumes and economies of scale is always welcome," BMW Chief Financial Officer Friedrich Eichiner told Reuters on the sidelines of an event to launch the electric inner city vehicle i3 on Friday.
Volkswagen surprised BMW in February by acquiring an 8 percent stake in SGL as a way to secure a supply of carbon fibers, a key technology needed to make cars more lightweight and fuel efficient. It has since then raised its stake to almost 10 percent.
In response, Germany's richest woman and BMW investor Susanne Klatten raised her stake in SGL to almost 30 percent, a so-called blocking stake which is sufficient to prevent outside companies influencing corporate strategy.
Klatten, an heiress to the fortune of German industrialist Herbert Quandt, previously held 22 percent. She holds 12.6 percent in BMW, while the Quandt family owns a combined 46.7 percent of BMW.
In October 2009, SGL struck a cooperation deal with BMW on lightweight carbon parts for its i3 electric vehicle, also known as the MegaCity project, a few months after Klatten emerged as a major shareholder in SGL.
SGL has since said it does not rule out collaboration agreements with other carmakers.
The use of carbon fiber reinforced plastics (CFRP), which are 30 percent lighter than aluminium and 50 percent lighter than steel, is one of the hottest trends in the car industry's drive to lower its carbon-dioxide emissions.