BMW N52 fuel and mileage

Btw, 2008 X3 3.0si

2750 rpms / 75 mph
3000 rpms / 83 mph
3250 rpms / 90 mph

Slippery said:

Btw, 2008 X3 3.0si

2750 rpms / 75 mph
3000 rpms / 83 mph
3250 rpms / 90 mph

my 2010 128i is almost exactly the same (probably by design lol)

Well, would you look at that!

Robbie (Forum Supporter) said:

In reply to AngryCorvair (Forum Supporter) :

I do get the knock sensing thing. I remember being told by Alfa that knock sensing above about 3k rpm is just a crapshoot because there is so much noise in the engine. I got the sense that knock sensing is not nearly as foolproof as it seems. 

It is extremely engine-dependent. I cannot speak to the N52, but I have seen the OE process, and it is extremely scientific. At the high end, they use spark plugs with embedded pressure transducers, and you can see knock in each cylinder. This signal is compared to what the knock sensor saw (or didn't see), and filtering parameters are tweaked until the knock sensor sees knock when it happens. Sometimes, no combination of filter parameters and thresholds will pick up knock without false positives. Even if it can't see knock in all the sensors, it has good odds of seeing it in some of them. 

Slippery said:

What speed are you guys running in top gear at 2750 and 3000 rpm?

I will check tomorrow, but seem to remember between 75-80 at those engine speeds. 

76 @ 2750 (cruise set speed 81)
83 @ 3000 (cruise set speed 88)