I no longer have my Z4 but would like to comment on paddle shifting and SMG as well. I never got to drive my Z4 on a track or even put it to its limits on the road. My previous car was a Boxster S with Tiptronic transmission, and although the rocker switches were not as easy to operate as paddles, they worked well and I enjoyed using them. I found that I could blast into a tight corner and downshift while at a speed far in excess of what was allowable, resulting in preselecting a gear for accelerating out of the corner without having to change gears while negotiating such corner with both hands and both feet busy. I am sure that the Zed would perform similarly.
re the SMG transmission, that is what I have now in my 2006 M6 coupe. The ratios (7) seem OK, but I find that I have to back off the throttle a bit at each transition in order to get a smoother change. This defeats the purpose of having a potentially fast-changing transmission. I just don't think that having things go "CLUNK" under me is not going to be expensive some day in the future. I have only had the car about six weeks so far, so the novelty has not yet worn off and the fuel bills are still horrendous. Maybe if I can leave that "M" button alone for a while, the consumption may improve a bit. But, it is fun to play with 507 HP, and at age 77 now, in three years or so, I may not be allowed to do so ?
David, in Brighton, ON, Canada