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Hi. I've been looking around for the EPA numbers on the M3/M4, which "should" be out soon?! Anyway I was surprised to see the M6 6-spd manual had better fuel economy (15/22) numbers than the 7-spd M-DCT (14/20).
Note, these are the same numbers as 2014, and for the Coupe as well as the M5. What surprised me was the relative standing of the manual and M-DCT. The relationship between the relative gearing in the manual and M-DCT is roughly the same in the M3/4 as it is in the M5/6, and this makes me now wonder if the manual will be rated with higher mileage in the M3/4 similar to how it is in the M5/6?
It is my understanding the M-DCT has the same (internal) gear ratios in these applications, but all M5/6s have a 3.15 final drive while all M3/4s have a 3.46 final drive. The manual in the M5/6 covers the ratio range 4.06 to .87 while the one in the M3/4 is a very similar 4.11 to .85 (the M-DCT covers a notably wider 4.80 to .67).
So, again I'm surprised the M-DCT (in the M5/6) is rated with lower milage by the US EPA. And I don't know what would be so different in the M3/4 that would reverse the relative ratings in that application? But multiple first-drive reviews have stated the M-DCT will get better mileage than the manual...
2015 BMW M6 Gran Coupe
AM-S7, 4.4L, 8cyl 16 14/20 $3,750 3 P T Tax SS
M-6, 4.4L, 8cyl 17 15/22 $3,550 4 P T Tax SS
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