What is it?
BMW maintains there's no case for an M version of the Z4, so unless the demand for hot roadsters suddenly goes ballistic, the 35is, which we've now driven in the UK, is the fastest variant we'll get.
At 335bhp, the 35is has 33 more bhp than the regular 35i. There are some visual tweaks but chassis changes are limited.
What's it like?
Faster, certainly. Beyond a freer flowing exhaust there are no mechanical changes to the 35is's motor over the 35i's. That's okay – the turbocharged 3.0-litre 'six was already a stonker.
The way the 35is picks up and pulls cleanly through its rev range is world-class, and now it comes with the kind of exhaust rasp that's been missing from the line-up since the demise of the old M3. Economy and emissions are on a par with the regular 35i, too.
A seven-speed dual-clutch transmission is standard and, save for the usual second-first hesitancy when manoeuvring, it shifts cleanly.
It constitutes part of a generous standard kit-list that also includes lowered suspension with adaptive dampers and the option to choose between Normal, Sport and Sport+ settings.
Sport+ is hopeless on anything rougher than a kitchen floor. While I'd like to say that Normal is too soft and the middling setting, Sport, has a level of rightness of which Goldilocks would approve; the truth is that to varying degrees both pull off the impressive feat of having a ride that's too harsh and body control that's too loose. More chassis development outside Germany probably wouldn't hurt
Oh, that's on the (new-look) 18-inch wheels, by the way. Unless you want to make your Z4 considerably worse – though apparently 60 per cent of UK buyers do – do not opt for the 19-inch wheels, which remove all vestiges of ride quality for no discernible upside.
Should I buy one?
Maybe. Like other Z4s the 35is lacks the precision and poise of a Boxster, but steering feel has been slightly improved thanks a mildly re-worked rack, and there's still fun to be had – with equal weight distribution, rear-drive and 335bhp, how could there not be?
But the entertainment provided remains of the old-fashioned, point and squirt variety. BMW's M division could probably do a job on it.