The 20-inch Bovensiepen forged wheels, which feature ten long double spokes, are designed to reduce weight, enhancing the roadster’s agility and comfort. They’re wrapped in a set of Michelin Pilot Sport 4S tyres, while the car’s dampers have been retuned to make the most of the high-performance rubber and boost responsiveness.

Beneath the Spider’s long bonnet is the 3.0-litre twin-turbo straight six that used to make 335bhp in the Z4 M40i. But Bovensiepen has fettled it to deliver 429bhp and 580Nm of torque, which is enough grunt for 0-62mph in 4.2 seconds. Top speed is 183mph with the optional Performance Package, making this the fastest ever version of BMW’s two-seater sports car. 

The engine’s intake system has been modified for more airflow, and Bovensiepen has added a new sports exhaust system that delivers a sound which is claimed to be “exhilarating”. The company says cooling is better now, too, but the aforementioned Performance Package also adds a new aluminium rear differential cover with larger fans to suit high-speed motorway driving, perfect for Germany’s autobahns. 

Sadly, the Bovensiepen Spider doesn’t feature the six-speed manual that made its way into the Z4 towards the end of its run. Instead, it gets the standard ZF eight-speed auto. Meanwhile, the rest of the interior has been retrimmed in more luxurious full-grain leather and Alcantara.

Discerning drop-top fans can order a Bovensiepen Spider now, with prices starting from 115,000 euros – just over £99,000 at the current exchange rate, making it more expensive than a BMW M4 Convertible. You can purchase a BMW Z4 for as little as £7,000 through the Auto Express Buy A Car service.

Bovensiepen is only making 99 examples of its drop-top  The company says 40 will be finished in Sapphire Black, 25 in Sanremo Green, 20 in Skyscraper Grey, 9 in Thundernight and 5 in Frozen Grey II. However, customers can request a new colour of their choice, presumably for a hefty fee. Deliveries are set to begin early next year, just in time for summer.