The phrase is “convergent evolution,” and it refers to a process by which biologically different creatures are shaped into similarity by the forces of their environment. As an example, flight has evolved in four different time frames across birds, pterosaurs, bats, and insects. There have also been five different kinds of animals which kinda looked and acted like crocodiles over the past few hundred million years; the first was an amphibian and the last was Ambulocetus, a crocodile-shaped whale.
Don’t worry, this isn’t Hagerty’s Guide To Biological Morphology, and your Web browser isn’t malfunctioning. It’s just my attempt to explain why the BMW Z4 M40i steers, accelerates, handles, and even kinda looks like an SL or SLK variant from the nice people at Mercedes-AMG. There was once a time when BMW M cars and AMG-built Benzes had very little in common, but that was before the world market for performance cars forced them into a sort of convergent evolution.
You sit low in the Z4, at least by modern standards. The steering wheel is positioned at chest height, with adequate adjustability. If you didn’t know you were driving a $70,000 car, the interior wouldn’t do much to tell you, although compared to what buyers of the original South-Carolina-built Z3 this is a quantum leap in materials quality. Overall room is Corvette-tight, not Miata-cramped.
The main attraction is the engine—BMW’s omnipresent 3.0-liter turbo, tuned here to 382 horsepower (@ 6500 rpm ) and twisting out 369 lb-ft (at a diesel 1600 rpm) through an utterly conventional eight-speed automatic transmission. The English auto writer LJK Setright once said something to the effect of, “An automatic transmission and turbocharged engine are perfect partners, because one will be at work when the other is not.” In other words, once upon a time, if you floored the throttle in an automatic turbo car, you’d get a downshift to produce some forward progress while the turbo started to spin up pressure. Setright died in 2005, too soon to see BMW invalidate his dictum with this profoundly indecisive and economy-obsessed eight-speed.
When it’s in the right gear and the turbo has spooled, this is a rocketship that shouldn’t fall too far behind late-model Corvettes at a stoplight. The rest of the time, you’ll be begging the transmission to stop wandering three or even four ratios away from an enthusiast-appropriate selection. No combination of sporty button-pressing can dissuade it. Around BMW’s track in Spartanburg, the Z4 would upshift while braking for corner entry at ABS-activation levels, leading it to be in fourth or fifth gear at corner exit when second or third was required. Cue a glacial gear change, followed by boost spool, followed immediately by the intervention of the traction-control system. You’re best off leaving it in manual mode and accepting the remarkably tardy manner in which the transmission responds to a request for a shift.
At least you’ll have no trouble slowing down. The Z4’s level of brake is more than adequate for the power on offer, although your author briefly set the left front pads on fire after failing to cool them down on-track. This 3500-pound convertible is also fairly eager to change direction, although the staggered tire sizes (front: 255/35ZR-19, rear: 275/35ZR-19) have a predictable effect, and the nose will always slide before the tail unless you’re misapplying the throttle. The razor’s edge balance of the old M Roadsters has been traded here for a luxury-car approach, the hood rising and falling ahead of you like a speedboat with each acceleration.
With all the driver-protection systems switched off, it’s possible to use the Bimmer’s power to force-adjust each corner, long wisps of smoke curling from the rear tires’ edges on the exit, the transmission bullied into compliance with frequent and attentive tugs at the paddles. It’s satisfying enough in short doses, but it’s also exactly how you’d drive the turn-of-the-last-decade AMG convertibles, not the Z4M or Z3-based M Roadster with which they competed.
In short, what we have here is a very fast luxury drop top. Nothing more, but also nothing less. It’s a few grand more expensive than the equivalent AMG SLC 43, but from certain angles it looks and feels a bit more adult, slightly more full-sized, than that baby Benz. No doubt the relatively small demographic at which it’s pitched will eat it right up.
Convergent evolution isn’t just evolution towards a form. It’s also evolution away from one. The BMW of a decade ago was happy to offer a stick-shift hardtop take on the Z4; that car didn’t find many buyers, but it was just short of legendary among the people who did take one home.
There’s no longer a clutch pedal to be had in a Z4, but if you want your hardtop to be permanent and not retractable you could go over to the Toyota dealer. The Supra is mechanically identical to this Z4, tuned in a few ways to deliver a slightly more engaging experience for the driver, and significantly cheaper as well. There’s no biology term of which I’m aware to describe the process by which Toyota came to be selling rebadged Bimmers—but there are more things in heaven and earth than are dreamt of in my amateur morphology.