Bovensiepen, the new automotive marque founded by the creators of Alpina, has revealed the Spider, a limited-production roadster based on the BMW Z4 M40i. With 429bhp, a 183mph top speed and production capped at just 99 examples, the Spider is designed to preserve the appeal of the lightweight, two-seat sports car in an increasingly SUV-dominated market.

The BMW Z4 may have reached the end of its production run, but its story is far from over. Bovensiepen, the marque established by the former Alpina founders, has transformed the latest Z4 into a bespoke performance roadster that combines more power, sharper dynamics and the kind of handcrafted luxury that made Alpina famous.
Called the Bovensiepen Spider, the new model is the company’s third production car, following the £320,000 Zagato coupé and the £144,000 05 GT estate. It is also the brand’s first convertible, although its connection to the Z4 goes back much further than its recent launch.
The Spider is, in many ways, a modern successor to the Alpina Roadster S, the Z4-based roadster created by the same team around two decades ago. This time, however, Bovensiepen has taken the latest-generation Z4 M40i and developed it into a considerably more powerful and exclusive machine.
Only 99 examples will be built, with deliveries scheduled to begin in early 2027. Despite its limited production and bespoke engineering, the Spider is positioned below Bovensiepen’s other models, with a German price equivalent to approximately £99,000—roughly the same territory as a new BMW M4 Convertible.
A 429bhp Straight-Six Roadster
At the heart of the Bovensiepen Spider is BMW’s familiar 3.0-litre turbocharged straight-six engine. In standard Z4 M40i specification, the unit already delivers strong performance, but Bovensiepen has substantially increased its output to 429bhp and 428lb ft of torque.

That is enough to propel the Spider from 0 to 62mph in 4.2 seconds, while the top speed rises to 183mph. According to Bovensiepen, those figures make the Spider quicker than any previous version of the BMW Z4.
The engine has not simply been given a software upgrade. Bovensiepen has reworked the intake system to help it breathe more freely, while a redesigned exhaust system has been optimised for improved gas flow and a more exhilarating, sporty soundtrack.
Cooling has also been upgraded to ensure the engine can maintain peak performance under demanding conditions. Buyers seeking even greater capability can specify an optional Performance Pack, which adds enhanced differential heat management to improve performance during sustained high-load driving.
Sharper Handling, More Grip
The Spider’s performance upgrades extend beyond its engine. Bovensiepen has retuned the dampers to improve responsiveness and give the roadster a more focused driving character.
The suspension is supported by Michelin Pilot Sport 4S tyres, fitted to lightweight forged wheels. These high-performance tyres are intended to provide the grip necessary to exploit the Spider’s additional power, while optional high-performance brakes offer buyers the opportunity to further enhance its stopping ability.
Unlike the Z4’s recently available six-speed manual option, the Bovensiepen Spider uses the standard ZF eight-speed automatic transmission. That decision prioritises rapid, consistent performance and reflects the marque’s focus on delivering a refined but engaging driving experience.
A More Exclusive Take on the Z4 Interior
Bovensiepen has retained the basic architecture of the BMW Z4’s cabin, but the interior has been extensively retrimmed using premium materials.

The seats are available in Vernasca leather, while the steering wheel is finished in Lavalina leather. Alcantara is used around the windscreen surround, adding a more sporting feel to the cabin.
As with the company’s other models, personalisation is a major part of the Spider’s appeal. The Bovensiepen Saddlery customisation programme is designed to offer a level of individual specification comparable with Bentley’s Mulliner or Aston Martin’s Q division.
Customers can work with the company to create a highly personalised car, with options including Alcantara boot lining, bespoke headrests and custom embroidery. These details are intended to make each Spider feel less like a conventional production sports car and more like a collector’s commission.
Bovensiepen’s Answer to the Disappearing Roadster
Bovensiepen says the Spider was created in response to a broader change in the automotive industry. Modern cars are becoming larger, heavier and increasingly influenced by SUV design, while traditional lightweight two-seat roadsters are becoming harder to find.

The company describes the Spider as a deliberate effort to preserve a vehicle class that has long represented one of the most direct forms of driving pleasure.
Its philosophy is summed up by the phrase “fine driving”—a concept that places emphasis not only on outright performance, but also on balance, craftsmanship and the experience behind the wheel.
The result is a car that occupies an interesting position in the market. It is based on a BMW Z4, but its limited production, increased power, bespoke materials and extensive customisation move it well beyond the standard model.
Price, Production and Availability
The Bovensiepen Spider will be limited to 99 units worldwide, with deliveries expected to start in early 2027. Its German price is approximately £99,000, making it significantly more accessible than the marque’s Zagato coupé and 05 GT estate.
For buyers looking for a rare, handcrafted performance convertible, the Spider offers a compelling combination of BMW straight-six power, Alpina-inspired engineering and exclusive ownership appeal.

Bovensiepen Spider: Key Specifications
- Engine: 3.0-litre turbocharged straight-six
- Power: 429bhp
- Torque: 428lb ft
- 0–62mph: 4.2 seconds
- Top speed: 183mph
- Transmission: ZF eight-speed automatic
- Base model: BMW Z4 M40i
- Tyres: Michelin Pilot Sport 4S
- Production: 99 examples
- Deliveries: Early 2027
- German price: Approximately £99,000 equivalent
Source: Bovensiepen


