Why not the BMW 6-speed manual gearbox which can be ordered in the 340i with this engine. Much more in keeping with a mog, lighter and more fun.
I would think the potential owners it's aimed at would expect an auto, and don't forget it's got a sort of semi-manual mode via paddles or gearstick, if you've ever spent hours in traffic jams crawling on & off the clutch in a Roadster

you'd like an auto option