 Complete the following phrase:  In 1967, the Formula 2 regulations were changed to allow 1600 cc motors, and BMWs new management was more open to the idea of open wheel racing. The BMW M10 block with a radial four-valve cylinder head designed by Ludwig Apfelbeck was used for some time. In the 1968 season, the company joined with Lola, using their 100 chassis. BMW sponsored drivers Jo Siffert and Hubert Hahne. For 1969, the team switched to Lola 102s, and used a new development of BMWs 1600 cc engine, dubbed the M12. Siffert and Hahne remained; Gerhard Mitter and Dieter Quester shared a third car. Halfway through the season, BMW debuted their own chassis, the 269, at the Hockenheimring. However, Mitter was killed in the 269 during practise for the 