My X3 has always had issue with shifting the auto transmission. For example, when simply driving down the road and with no appreciable throttle input the tranny will suddenly shift down and the engine will rev to maintain speed. It's just not "right".

I spoke to the dealer about it, and they put it off as "works as designed". One tech even said it's because the car tends to be underpowered. They did disconnect the battery to clear the transmission program so it could "re-learn" my driving style, but the "feature" remains, and I had decided to live with it.

I was thinking about it the other day and suddenly wondered if the Dinan programming might correct it. The 3.0 engine could use a little more "oomph" in any case, and the Performance Program at 299 seems reasonable, especially if I get a bit more performance from the car and get rid of the shift issue.

Anyone have any thoughts? The only other question becomes, will the software work for a 2008? They only list through 2006.

If they have a try it before you buy it policy, it might be worth looking into. The car goes in Tuesday and it might be good opportunity to load it up.