Complex sentence: This was the same powerful BMW M12 Straight 4 which was also used by the Brabham team, though unlike Brabham who had BMW engineers looking after their engines, the Arrows engines were maintained and developed by Swiss engine guru Heini Mader.
Split into simpler sentences: This was the same powerful BMW M12 Straight 4 which was also used by the Brabham team. The engines were maintained and developed by Swiss engine guru Heini Mader.