I've run up to 85 mph will in the sport mode and the tranny stays in 5th. I've not found anything in the manual reference to this.

 

I think you'll have to run it up quite a bit higher, but not sure if it will still shift to the last gear before the speed limiter cuts in. I can hit the 155mph in my 335i in 5th gear and don't need the 6th gear, it's only for mpg on the highway. My normal driving 60-80mph and in sport mode step, the bimmer never leaves 4th.

I wish my MCS was here so I could go check for ya...cause I would.

 

Yeah I've never really pushed it, but it always seems to say in fifth for me. I end up just going to the manual shift Sport and put it into 6th.

 

when its in sport mode, fifth is your top gear. However, if you run in manual shift mode, you can upshift to sixth with a lever tap.

I run mine like this most of the time. I do not find the extart weight of the steering that big a difference and the manual shift mode is more flexible than using sport mode.