In Reply to: Q for Techies: What is a vanos? (more) posted by JWR on October 24, 2000 at 12:05:07:
I am sure you have heard of Honda's VTEC or Toyota's VVTi...same idea. It varies the cam position to maximize low end torque and high end power (with fixed cam timing you have one or the other, not both).
Not all engines have it. Not all engines have it. Not all BMWs have double VaNoS (notice the way it is typed- it does matter). Single VaNoS (intake) was implemented on the E36 for MY93. The Z3 and E46 got double VaNoS for MY99. The 4.4L V8 didn't get any VaNoS until MY00- and it only has on the exhaust side (I think it will get double VaNoS soon). The E39 M5 has double VaNoS. I don't think the V12 has either, but I could be wrong.
Double VaNoS allows infinite (different than Honda VTEC which only has 2 cam positions) adjustment and one by product is better emissions and gas milegage.