Car shifts to Neutral at speed

[jamesboags]

Hi All , I reported some tranmission issues a while ago took it to the dealer and was given the "can't replicate the problem". Car is a 2007 3.0 Diesel.

Yesterday the car had another issue at the same place & same driving conditions some 200 km out of Sydney (so I can't take my service guy there to see it for himself !!).

I was driving at approximately 70 km/h on the entrance to the freeway which is on a slight downward slope, foot was off accelerator (vehicle coasting in Drive to maintain speed limit) , not sure what gear the car was in but I'd presume 5th , this was just prior to merging and attempting to accelerate to 110 km/h.
On acceleration, the vehicle of it’s own accord shifted to Neutral, engine did not stall, first evidence of neutral was that when I attempted to accelerate the engine freely revved up to 5000 rpm (I was watching the mirror at this time preparing to merge to the traffic moving at 110 km/h), No warning lights or chimes.. At this stage several cars travelling at 110 km/h including a large truck had to slow to avoid my vehicle which was unable to maintain a speed above 70 kmh. An extremely dangerous situation, I had my wife and 16 month old in the vehicle !
Car was placed in Drive again from Neutral with car rolling at approx 70 km/h and a second attempt at trying to get to highway speed caused the vehicle to go to Neutral again, it was observed at this time that vehicle Tacho went from 4000 rpm to 0 then back to idle speed...previously had a problem with the car changing with a "Thud" and searching for gears at the exact same place !!! It does not occur in normal driving conditions arund town (max 80 kmh on expressway)..... ... It would appear the engine is cutting out and the car is going to Neutral... It's extremely dangerous when this occurs... I am writing a letter to BMW to detail the situation and my request for a proactive diagnostic approach at my next service appointment...rather than everything looks ok , no check control messages stored & the usual warranty blurb.... Any ideas or comments welcomed.. maybe a software update woudl fix (or at least should be one of the first things they do? ) ?