Hi Rosino,
This is a warranty issue and as such will be fixed by any BMW dealership FOC. Which dealer is telling you these porkies? Please name and shame.
I stongly advise you take you car to another dealer who will do the software upgrade under warranty. You may be well advised to contact Anneka at Sytner through the forum. If no joy there then please contact BMW UK and complain as THIS IS A SAFETY ISSUE in my opinion!!!
I'm retyping my reply to your initial post on this topic below which as you can see states a new release of the software summer 2009 to which my car was upgraded FOC and is now a pleasure to drive
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Just searched out the SIB info and posting it here for you...
http://www.bmwtis.com/tsb/bulletins/...p/B280708g.htm
This shows that BMW were clearly aware of the problem some time ago. It states categorically "To significantly improve the throttle response (or to reduce "throttle lag"), reprogram the vehicle with the current ISTA/P version (target integration E089-09-03-510 or higher, introduced in ISTA/P 2.33.1)." Have you printed this out and shown the dealer?
Basically this states that the problem is fixed from software version 2.33.1 onwards. I believe mine was updated to 2.34.1 last July and I haven't had the lag issue since and I drive 99% of the time in D2.
Good luck in getting this addressed and as I said in my previous post it's shocking that a BMW dealer can sell the car without this update which addresses a potentially dangerous issue."
Good luck!