What BMW has done, however, is to entirely redesign the car’s suspension (struts featuring up front and, for the first time in a Z4, a five-link system at the rear). Lightweight aluminium components have been adopted to save on unsprung mass, while new subframe mounting techniques have been used at both ends and the tracks are wider – by a significant 98mm at the front.
At launch, buyers will be able to choose between 194bhp and 255bhp turbocharged 2.0-litre petrol engines in the 20i and 30i respectively. A 3.0-litre turbo straight six (M40i), with M Performance derivative status, glitters away temptingly at the top of the range and is endowed with 335bhp and 369lb ft of torque (which, Z4 fans will note, is actually no more grunt than the outgoing Z4 sDrive35iS had).
The headline version of the new car gets lightweight 18in alloy wheels as standard, as well as an eight-speed automatic gearbox, lowered and adaptively damped sport suspension, uprated brakes and a torque-vectoring electronic locking differential.
How the Z4 was built around its soft-top roof
It’s pleasing to note that the car industry’s elongated dabble with the folding metal hard-top is now mostly over. Cloth hoods are lighter, simpler and easier to package, all of which makes them a much better fit for any sports car. They seem to be able to seal a cabin at speed almost as well as a hard-top would these days.
They also reaffirm the central point about any convertible, it seems to me, via that sense of visual impermanence. A cloth hood on a sports car is like Gene Kelly’s fedora, or an umbrella over the barbeque: it’s a joyous thing. When it’s up, you can tell it’s only up under sufferance, and it’ll be down again to let the sunshine in and the good times roll before you know it.
The new Z4’s roof is nicer to look at than most. BMW supplies it in black as standard, but our test car’s came in anthracite grey with a silver fleck that made it look a bit like designer denim. Squeeze underneath that hood and you’ll find a driving position that isn’t set quite as far back as the Z4’s once was. It used to feel as if you were sitting right on the rear axle, with acres of metalwork out in front of you. That’s not quite true of the new version; you’re usefully closer to the middle of the wheelbase, positioned low and nicely out of the wind, and with plenty of room for your legs and elbows.
How does the Z4 perform on the road?
The Z4 features BMW’s new-generation ‘Live Cockpit Professional’ digital instruments and its ‘BMW Operating System 7.0’ infotainment set-up. It’s also the first Z4 with a head-up display. The latter is optional but probably worth having, because those new digital instruments aren’t as easy to read at a glance as they might be.
You’ll need to keep a wary eye on that speedo, too, because the Z4 M40i can certainly stretch its legs. The car’s turbo straight six pulls with lots of guts and great throttle response from low crank speeds, and keeps pulling with smoothness and freedom in its delivery as well as with force. BMW’s preference to dial in contrived engine noise in the car’s more dynamic drive modes might be a bugbear for some, but drop the Z4’s roof and the foible becomes less annoying than it might be in a saloon or coupé, with more genuine exhaust and induction sound reaching your ears through the fresh air rushing around your head.
And what of the rest of the driving experience; should those 718 Boxster owners get ready to jump ship? I dare say some will - but I wouldn’t be in a mad rush.