The story
History: facts, each with the kind of source it rests on
VANOS is the variable valve timing BMW has used on petrol engines since 1992, first on the M50 in the 3 and 5 Series. The name shortens the German words for variable camshaft timing. A published reference
The first version, later called single VANOS, worked on the intake camshaft only. Double VANOS works on both the intake and exhaust camshafts, first on the S50B32 in 1996. It retards the camshafts at low speed for a smooth idle, advances them in the middle for torque and economy, and retards them again for full power. A published reference