i had the same issue. it started out as a noticable shudder between gears mostly around 35-40mph and light throttle. When driven in sport, that seemed to help. We drove it that way for about a year and then the trans fail safe went off and when warm, it would rev up and then slam into gear from a stop or low gears.

transmission shop and independent bmw shop both said the tranny needed the dreaded rebuild. Just called the tranny shop today and turns out a bearing went out and caused some tolerance issues. He said he sees it all the time on these transmissions,..

bite the bullet. he's estimating about $4,500 OTD