BMW550i'06,automatic transmission, will not downshift from 6th on its own,funny straining noise,ok when warm

Question

11 mths old, problem since purchase. Accelerate from stop position to 50 km per hour and car is in 6th gear; then coast to slow down to 35km/hr. If then want to increase speed slowly, say to 40km/hr, no downshift occurs to 5th or other gear and straining unnatural noise is heard till get back to 45 km/hr. Car always stays in 6th throughout. After 15 minutes, car warms up and transmission is normal. That is, it will drive and accelerate at even 30 km/hr and smoothly, although with little torque but no abnormal straining noise. It should downshift automatically at such low speeds when accelerating.

Answer 1

Your car should still be under warranty. The diagnostic equipment at the dealership can detect even minor flaws in operations of nearly all equipment in your BMW, even down to radio operation. They use an umbilicus that attaches to your car's diagnostic terminal. You would be foolish to let anyone besides an authorized BMW dealer to look into your problem. There might even be a recall on this thing. Either way,BMW should pick up the tab!!!