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# BMW Z4 gets more power than a Toyota Supra
- URL: https://torquecafe.com/car-news-2026-bovensiepen-spider-bmw-z4-upgrade/
- Published: 2026-09-14T01:36:43.000Z
- Updated: 2026-09-14T01:36:43.000Z
- Description: The founding family of Alpina have given the BMW Z4 the M-inspired tune-up many thought it needed, unveiling the Bovensiepen Spider.
- Author: Jordan Mulach
- Tags: News, Performance

BMW may have already wrapped up production of the Z4 convertible and its Toyota Supra coupe twin, but that doesn’t mean the drop-top is completely dead, having recently had its life extended thanks to Bovensiepen.

Founded by the family which started Alpina – now under full control of BMW – Bovensiepen’s vehicles are arguably a continuation of the brand formerly owned by its namesakes, providing performance upgrades while keeping its vehicles classy.

The Bovensiepen Spider is no exception, taking the BMW Z4 and dressing it up in a nicer suit, while hiding the extra weight training it’s been doing underneath.

![](https://storage.ghost.io/c/a9/b3/a9b3e204-3117-4792-9a32-46184029df44/content/images/2026/09/Bovensiepen_Spider_03-1.jpg)

Bovensiepen Spider

Visually, the Spider stands out from the Z4 with its tweaked front splitter, wheel-arch vents, more prominent side skirts and a sharp rear diffuser, sitting below the extended rear spoiler which stretches the overall length of the convertible.

This design package was penned by famed automotive designer Frank Stephenson, who counts the first-generation BMW X5, the first BMW-era Mini, the McLaren P1 and Ferrari F430 as just some of his designs, and who in June helped unveil the [Bovensiepen 05 GT](https://torquecafe.com/former-ferrari-mclaren-designer-puts-the-bmw-m5-in-a-tuxedo/) as a classier BMW M5.

The wheel design of the Spider has also been reworked, with its 20-inch forged alloy wheels featuring 10 spokes – half the number of Alpina’s classic design – sitting in front of larger optional brakes, with four-piston calipers and 395mm rotors at the front teamed with 345mm discs at the back.

![](https://storage.ghost.io/c/a9/b3/a9b3e204-3117-4792-9a32-46184029df44/content/images/2026/09/Bovensiepen_Spider_06-1.jpg)

Bovensiepen Spider

Bovensiepen’s brake upgrades are a hint at what other changes have been made under the skin, such as retuned dampers with higher low-speed compression, while at the rear there’s longer auxiliary springs.

However, the biggest upgrades have been made under the bonnet, where a ram air intake, larger intake silencer, new sports exhaust, and other changes have resulted in the Spider producing 320kW and 580Nm from its turbocharged 3.0-litre straight-six engine.

For context, the standard Z4 M40i made 250kW and 500Nm, the GR Supra produced 285kW and 500Nm, and the send-off GR Supra Final Edition made 320kW and 570Nm, making the Spider more powerful than the lot.

In base guise, Bovensiepen claims the Spider will sprint from 0-100km/h in 4.2 seconds (identical to the Z4 upon which it’s based), while it’ll hit a limited top speed of 260km/h.

![](https://storage.ghost.io/c/a9/b3/a9b3e204-3117-4792-9a32-46184029df44/content/images/2026/09/Bovensiepen_Spider_05-1.jpg)

Bovensiepen Spider

With its optional Performance Package, the top speed rises to 295km/h, and its structural rigidity is increased thanks to the fitment of a V-brace under the skin. Also included is a rear differential cover with larger cooling fins.

The Bovensiepen Spider is auto-only, with the eight-speed ZF transmission the only one on offer, its gear selector appearing in the cabin which is now kitted out with standard Vernasca leather and Alcantara upholstery.

The heated steering wheel is wrapped in Lavalina leather, while customers can request their own interior appointments through the Bovensiepen Saddlery program.

Just 99 examples of the Spider will be made, priced from €115,000 (A$186,500).