People have always treated the Z4 a little bit differently from the rest of the BMW lineup. Early generations boasted polarizing looks, and it never readily shared much with other BMW products. Being shorter and wider than high-production models like the 3 Series and 4 Series but falling short of the motorsport theater accompanying the full-blown M products made the Z4 – and its Z3 predecessor – always a little bit of an anomaly.
Not much changed with the introduction of the G29 Z4 for the 2019 model year. Sharing production with Toyota’s Supra made fans of both brands inexplicably malevolent toward the platform. Moreover, without a true M variant, the M enthusiasts were never terribly concerned with it, opting instead for (slightly) heavier and bigger M3s and M4s. However, a recent chat with Michael Wimbeck, Project Manager for the Z4, revealed some – heretofore unknown – tidbits about the Z4’s origins and production.
Unexpected Parts-Sharing and a Unique Platform
As one might expect – or already know – the Z4 Roadster shares some parts with many different BMWs. But not in the usual ways. The Z4 is technically built on the CLAR platform, but the only thing it shares with its platform mates is the rear axle. That’s right – one component. The front axle is constructed from aluminum and is positioned differently from a traditional CLAR vehicle to accommodate where the engine sits. If you didn’t know, it sits significantly further back on the Z4 than on other CLAR vehicles. Sensibly, it sits further toward the middle of the vehicle for optimal chassis balance.
Interestingly, this is a feature that at one time was shared with the G80 and G82 M3 and M4. Unfortunately, Wimbeck explains, BMW engineers needed to ditch this aluminum axle design as plans for an all-wheel drive variant became a reality. Technically, the Z4’s axle design is not identical to the G80 and G82 – but it’s very close. It shares many components and kinematics.
But in reality, only two things are shared with the Z4 across any BMW vehicle. The seats are pulled from the 1 Series and MINI – explaining their slightly smaller proportions. Wimbeck claims that the 3 Series firewall is the only other component the Z4 shares with other BMWs. Aside from that, everything is unique to the Z4.
The Importance of Tires
Every enthusiast knows that tires are integral when it comes to squeezing every bit of performance out of a car. While sometimes manufacturers develop a vehicle alongside a tire, the man responsible for the Z4’s driving dynamics opted for an alternative. Citing ease of finding tires, cost, and suspension tuning, Wimbeck says they borrowed the tires from the outgoing M3 and M4 instead. “Exactly the Michelin Pilot Sport from the F8X M3 and M4. It made it easier for him to tune the car around these tires,” he says.
BMW Supra? Not Exactly
Finally, Wimbeck was asked about Toyota’s contribution to the Z4 project. Truthfully, with so many BMW parts – i.e., the whole car – it has been unclear exactly how Toyota helped. While Wimbeck didn’t directly answer the question, he does explain how the two vehicles targeted different benchmarks and buyers.
“At the beginning, it was a little bit difficult to figure out how to find the size of the car, the wheelbase, the center of gravity, the engine position and the package of the car. Once we found that package, the tuning of the car was done at the specification from Toyota for the Supra. We kept our own specifications for the Z4, so essentially the two cars behave differently on the road.”
Now it all makes sense. The Z4, being a roadster, was never destined for hotlapping. From the beginning, a roadster design is naturally compromised in terms of rigidity and center of gravity. Either way, it’s nice to see that BMW isn’t afraid of spending some time and money developing a rewarding-to-drive car, even when it’s in no danger of breaking Nurburgring records.
So, bang away on your keyboard, simultaneously outraged that the new Supra “isn’t a Supra” and that the Z4 is “not even an M.” I have a hunch the Z4 owners will be too busy driving to be much bothered. Because – as you now know – it’s quite a bit more unique than every other vehicle on the road. Well, except for one.
