- Bovensiepen’s third model is based on BMW’s recently departed Z4 roadster.
- The donor Z4 M40i’s 3.0-liter inline six is boosted from only 335 hp to 429 hp.
- Frank Stephenson Design provides subtle styling mods, including rear spoiler.
The final BMW Z4 rolled off the Graz, Austria, production line in May, and while there are still cars hanging around dealer lots, your chances of speccing one to your taste are over. Or so we thought until we learned about the Bovensiepen Spider.
If you’re not familiar with the Bovensiepen name, you are almost certainly familiar with the four-wheeled work of the people behind it. The Bovensiepen family set up the Alpina brand in the 1960s and did such a great job of enhancing BMW cars in the intervening years that BMW bought it out, the final transfer taking place at the start of 2026.
Related: Alpina’s Founders Built A 790-HP BMW M5 Wagon That Looks Like A Lease Special
But it looks like BMWs are in the blood at Buchloë, the former Alpina base west of Munich. Since setting up a new company under his family name, Andreas Bovensiepen has revealed two new cars. The first was a BMW 4-Series re-styled by Zagato, though not enough to justify its crazy $435k price, in our opinion. And the second was the 05 GT, an enhanced M5 wagon that punches out 790 hp (800 PS) but somehow looks about as exciting as a zero-options, taxi-spec 530i.
So the Spider is the third model from the new brand, one created with the help of former Ferrari and McLaren designer Frank Stephenson. Its core is the Z4 M40i, BMW’s top Z4 since it never bothered making a Z4 M this time around. The M40i left European BMW dealers with 335 hp (340 PS) – it made 382 hp (382 PS) in the US – but breathing work on the 3.0-liter inline six’s intake and exhaust helps grow output to 429 hp (435 PS) along with 428 lb-ft (580 Nm).
The Automatic Choice
Bovensiepen says it’ll hit 62 mph (100 km/h) in 4.2 seconds, versus 4.5 seconds for the stock M40i with the same ZF eight-speed auto. BMW did offer a Handschalter six-speed manual M40i late in the model’s life, but that’s not an option here, sadly. It seems like a mistake, but then Alpina embraced the automatic transmission long before BMW’s M division did.
Other mods include retuned dampers lightweight forged wheels coated in grippy Michelin Pilot Sport 4S rubber. And if you’re planning to really rag this ragtop you can upgrade the Spyder with a Performance Package that includes a milled aluminum cover to keep the diff cool, an underbody V-brace and a top speed limiter increased from 162 mph (260 km/h) to 183 mph (295 km/h). A big-brake kit is also available.
How Many Cows Do You Want?
Visual tweaks marking the Spider out from the Z4 M40i besides those 20-inch rims are subtle, but include bespoke arch vents, a gloss black splitter, side skirts and a bigger real spoiler. Seats wear Vernasca leather and Alcantara and the steering wheel is wrapped in fancy Lavalina leather. But if you want the whole dashboard draped in hide, Bovensiepen can do that too.
Only 99 are planned and they’ll each cost from €115,500 ($134,000) in Germany including taxes. But a chat with the Bovensiepen Saddlery personalization team about a paint-to-sample color because you don’t like the five recommended hues, lining the trunk in Alcantara or adding custom upholstery will quickly inflate that number. Deliveries start in the first quarter of 2027, almost an entire year after BMW told us the Z4 was no more.
Bovensiepen
