I have battled this issue all the way up to the ZF engineer level. BMW is very protective of their CAFE (gas mileage) figures that they refuse to do any reprogramming on my 05 4.4i tranny. Please see my earlier threads on this topic.

I have had many software upgrades and still nothing. Works as designed and they refuse to fix it. And yes, mine stays in 4th gear around corners until I hit 17MPH - I measured this very specifically with the ZF engineer in my X with me. Mufflers shaking (bogging) and everything.

SO, I called Dinan and they said they would custom program me a new 3rd gear shift point that would kick in at about 22MPH, rather than 17. If in sport mode, 3rd kicks in at about 22 or 23MPH and it feels fine around corners. Down side is once you get to your driveway the SP mode engine braking will jerk all your pasengers into airline crash position.

Dinan said they will finally be done cracking the entire code for the 05 X in Spring, which will enable them to tweak the shift point without killing any other integrated engine management system. I plan to call them back in April to revisit this issue. Estimate cost: $800. This shouldn't have to play out like this....

Any other suggestions too put some leverage against BMW to fix this bogging down / shift point issue?

And yes, I've had my adaptive tranny software switch reset and I drove it like I stole it for about two weeks. No help

Thanks for listening to a re-rant.

Chris