It's not often a manufacturer admits it was wrong. You might get a PR team suggesting that a particular model wasn't successful because it was 'misunderstood' or 'ahead of its time', but an outright admission of a mistake? Not a chance. So you can imagine PH's surprise when current Z4 product designer Michael Wimbeck admitted to us over dinner - the night before we drove the car - that BMW went down the wrong path with its second-generation Z4. "We followed Mercedes with the hard top roof and softened the car off too much, but this time, with the third generation model, we've created a genuine driver's car. In benchmark testing we found it was closer to an M2 than an M140i. You'll see".
It was a refreshing and somewhat unexpected admission, but one that goes some way to reasserting the idea that BMW is once again focusing on the right audience - namely people like us. After all, the reason for the first generation Z4's unprecedented success was the fact it was so good to drive. Don't forget, it took BMW over a decade of experimenting with various iterations of two-seat sports cars - Z1, Z3 and Z8 - before its engineers stumbled across the ideal formula.
It is that formula that BMW has sought to return to with the third generation model which, on paper at least, certainly looks promising. Gone is the folding metal roof of its predecessor, replaced with a lighter cloth hood that helps to lower the Z4's centre of gravity, while the car of course sits on a whole new platform. Lightweight aluminium components have been used to reduce unsprung mass, new subframe mounting techniques have been applied at both ends to provide greater structural rigidity, a five-link setup has been adopted at the rear - the first time for a Z4 - and the tracks have been made significantly wider (the front by a substantial 98mm).
Of course, with the car growing in size (it's slightly longer, too) it is actually fractionally heavier than the Z4 it replaces, but BMW hopes the gains made elsewhere will make up for those extra kilos. Indeed, a Nurburgring lap time of 7min 55sec (a whole three seconds quicker than an M2) certainly goes some way to proving this; moreover, there's no ignoring that the range-topping M40i's 3.0-litre engine is both more powerful than a base Boxster's 2.0-litre motor and, with six cylinders, more tuneful as well.
Actually, in truth that latter point might be a little controversial, as it's immediately noticeable once behind the wheel that BMW has chosen to dial in some imitation engine noise through the car's speakers to help boost its aural charisma. Once you notice it, it quickly becomes a source of irritation - although at least it's escapable in the Z4; lose the roof and you've got a front row seat to genuine exhaust and induction noise.
And boy does it sound good here. In Sport Plus mode the exhaust pops and crackles on the overrun while the motor feels properly athletic, exhibiting virtually no turbo lag. Indeed, throttle response is exemplary, as is the motor's ability to rev cleanly all the way through to 6,500rpm. And despite only coming equipped with an automatic gearbox, keener drivers shouldn't be too disappointed - BMW's eight-speed unit is still one of the best around, delivering smooth, precise and reliable shifts on command.
But that's the easy bit. Six-cylinder Z4s have never been lacking in straight-line speed. What we really wanted to know was if BMW's engineers had succeeded in creating a truly rewarding driver's car. And on first acquaintance it would appear that they have - well, for the most part anyway. In terms of ride and handling, the new Z4 is a significant step on from its predecessor.
On the tight and twisty canyon roads just outside of Estoril, the Z4 impressed with fine body control and startling levels of lateral grip and traction - the front end feeling particularly keen to turn in regardless of corner entry speed. If judged purely on its raw ability to get from A to B, there's no doubt that it would give an Audi TT S roadster or a Boxster a run for its money on pace alone.
Delving deeper, though, it's clear this is still a Z4 limited somewhat by its 1,535kg kerbweight and sheer size. Even on Portugal's relatively accommodating country roads, the car requires unerring accuracy because of its significant width. Moreover, where the Z4's poise and grip initially impress, push closer to the limit and the balance feels nervous - oversteer is fine when it's induced, if rather less welcome when it arrives without warning.
That being said, the car never feels scary and some owners (perhaps those that already own an early F80 M3...) may even enjoy its prickly-on-the-limit nature. Ultimately though, you can't help feeling that its mass has hamstrung the dynamics, forcing BMW to build a car that favours brute force over delicacy and deftness, even when the optimum combination of settings for the Individual driving mode has been configured. An Alpine A110 this is not.
Arguably, of course, it doesn't need to be, and the Z4's considerable advances over its predecessor shouldn't be ignored. This is now a credible proposition for those after an accomplished roadster, one that on pace alone has the ability to take on the best from Stuttgart, Ingolstadt and Dieppe. But on pure driver appeal? It's just not quite there. The Z4 is just a little too heavy, a little too blunt, a little too soft around the edges to make it a truly stellar contender.
Still, with a more engaging powertrain than Porsche currently offers and better (i.e. rear-driven) handling than Audi provides, there's still a lot to recommend here. BMW has delivered an appealing blend of talents - more so than ever as far as the Z4 badge is concerned - which means it still ranks as a very competitive, if not wholly compelling, convertible sports car.
SPECIFICATION - BMW Z4 M40i
Engine: 2,998cc, straight-six turbo
Transmission: 8-speed automatic, rear-wheel drive
Power (hp): 340@5,000-6,500rpm
Torque (lb ft): 369@1,600-4,500rpm
Top speed: 155mph (limited)