It may have to do with the aggressiveness of the driving. If you hammer it, it will go high and shift late, if not, it will shift lower, but hang higher than in just D. try applying the same throttle on the same stretch of road and see if it is consistent or varies a lot. If I get a chance, I'll test and post results for you (it's the wife's car after all ).

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Daily Drivers:
- 2008 535i, 320,000km
- 2004 X5 4.4, 01/2004 production, 420,000km
- 1997 328i, 350,000km

Track:
- 1996 328i, track/race car, ~300,000km

Winter:
- 2013 Ski-Doo MXZ X 800 E-TEC, trail can
- 2007 Ski-Doo MXZ Blizzard 800 HO
- 2001 Ski-Doo MXZ 600 w/800 engine, exhaust
- 1978 Ski-Doo Olympique 340 (vintage race sled)
- 1977 Ski-Doo Olympique 340E