Quote:
Originally Posted by Red Bread
My M Coupe got 28-30 mpg running between 80-85 mph consistently and might have returned over 26 mpg when running triple digit speeds, in theory at least...
Admittingly, it was 800 plus pounds lighter than the X1. I am impressed with the X1 nearly matching the highway efficiency of our previous N54 135i, up to about 85, where it does seem to start dropping off much more than the 1er did.
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Also, the M Coupe has lower air resistance (drag), which will be more of a factor at higher speeds.
Does it have the same twin scroll turbo, or is it a twin turbo? The latter may be more efficient at medium-rpm coasting, but burning more getting there.
I also found this, which has data from a 2009 study:
http://cta.ornl.gov/data/tedb31/Edition31_Full_Doc.pdf
Page 118 (section 4-28) is the interesting one. As expected, it shows a larger drop in fuel economy for small SUVs than for "regular" cars as speed increases, and a drop from 34.3 mpg at 55 mph to 24.5 mpg at 75 mph. That's a
quite significant difference.
When the esteemed poster here reported 24-30 mpg at 75.5 mph, I think the N20 X1 is rather impressive.
