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      11-16-2012, 12:23 AM   #8
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Drives: ESS twin-turbo roadster (E89)
Join Date: Mar 2012
Location: European in China

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Originally Posted by morfinx View Post
Why would that affect fuel efficiency?
I am not sure if the sport button in the Z4 does the same as in the 1-series M coupe. If it does it would let the turbos run at higher "idle" speed and thereby reduce turbo lag. This creates more loss and worse mpg in some conditions.

And when you spin the wheels in sport+ you also get worse mpg. This would not happen in sport mode.

In DCT cars the gear shifting points and clutch speeds are also different in different modes. Due to the imperfectness of our gasoline engines, we get better mpg by selecting the highest gear possible at any given cruising speed.
Little known facts about BMW: 1) The N54 is still in production and used in the current Z4 35i and 35is. 2) In a Z4 you can get sport+ steering combined with normal suspension etc by selecting DSC=off. (Update: DSC=off also offers sports steering in the M135i) 3) All Z4s with 19" wheels are still only offered with the worst performing OEM tires ever sold with a DCT equipped BMW (Potenza RE 050 RFT).