Auto gearbox drops down and revs high when descending..

[upallnight]

It is known as engine braking, truck drivers are forbidden to do it on a highway next to a residential development.

[Qsilver7]

If the issue is coming from the adaptive feature of the tranny...you do have 2 ways to self adjust (aka opt out of the automatic selections made by ATC)...one way is what has been mentioned by owners in this thread which is to use the MANUAL selection of gears using the manual gear selection feature of STEPTRONIC.

The 2nd way is to use the SPORT mode of STEPTRONIC by pushing the gear select lever over into the "M/S" gate and leaving it there (at least just before you get to the area where the hill is and you hate the way the transmission may be automatically selecting the down hill drive program. The manually selected SPORT mode will interrupt the adaptive selections of ATC...and you still won't have to manually select the gears (if you don't feel like shifting).

Again, if the issue is coming from the adaptive HILL drive program of ATC...by selecting the SPORT or MANUAL gear selection (using STEPTRONIC) will change or take away the ATC (adaptive transmission control) selection of 1 of the 9 adaptive transmission programs that it selects based on driver input or road/environmental conditions:

The adaptive driver input feature of ATC will select 1 of 3 programs below by the way you mash the accelerator pedal:

• extreme economy (granny toe mode)
• economy
• sport

Environmental or road conditions features of ATC will automatically select one of the 6 modes below:

• stop-n-go mode (will select 2nd gear starts after a specific 1-2, 2-1, 1-2 gear shift & braking occurs below a specific MPH & time interval)
• winter mode (rear wheel slippage will cause 2nd gear starts {not sure if this applies to xDrive, though...which will adjust torque split to regain traction})
• up hill recognition program (higher engine load with lower speed)
• down hill recognition program (higher road speed with minimal throttle input)
• curve recognition (prevents upshifts when in a curve)
• cruise control drive program (shift map that prevents possible unwanted lock/unlocking of torque converter and upshifts/downshifts)

BMW tech info about some of the AGS (adaptive) features of ATC:

[j9mm0]

Thanks Qsilver7..
I think I'll try the steptronic mode first and see how it feels..