Back in 1989, after Mercedes introduced the SL R129 – a sophisticated two-passenger convertible with a removable hardtop designed as a modern successor to the classic SL range that included the Mercedes-Benz 300 SL Gullwing – an ambitious German engineer thought he could do better and ended up creating a one-of-a-kind vehicle that won the hearts of automotive fanatics and car collectors.
Hartmut Boschert from Emmendingen in the south of Germany had his own idea of what a modern SL should look like, so he embarked on an ambitious endeavor – that of creating an entirely modern version of the Mercedes-Benz 300SL Gullwing with no help from Mercedes whatsoever.
He didn’t work completely alone on the ambitious project, though, as he enlisted the help of famed Italian coachbuilding company Zagato. With unwavering determination and a mix of classic design elements and sophisticated modern technology, Boschert built a unique sports car, named it the Boschert B300 Gullwing, and presented it at the 1989 Frankfurt International Motor Show.
The unofficial custom car started life as a 1988 Mercedes 300 CE (W124), and the design included almost exclusively Mercedes parts and components. What makes it so special is the exquisite design with doors that open upwards, something that was missing on Mercedes’ official successor to the SL range. The gullwing doors were truly the highlight of the design as they held a certain nostalgic charm for automotive fans who remembered the Mercedes-Benz 300 SL introduced in 1954.
A lot of reengineering work went into this custom vehicle, as the initial doors of the donor car had to be removed and the C-pillar moved forward 9.9 inches (25 cm) to accommodate the new roof-hinged gullwing doors, which are so large that they provide access to both the front and rear seats at the same time.
Another 9.9 inches were cut out of the rear overhang to improve road handling. Moreover, the sills were moved up and the unibody reinforced, and the designer even grafted the front end of a Mercedes R129-generation SL onto the front of the car. That’s a lot of structural changes, and Zagato’s involvement in the design and execution is almost palpable, as the resulting machine looks like it was built by Mercedes themselves.
The German engineer’s initial plan was to manufacture 300 units of the Boschert B300 as a limited series, but that plan didn’t actually materialize. Only the initial B300 Gullwing and ten additional examples were ever built. The example you see pictured here is the only one with the trademark gullwing doors of the iconic 300 SL coupé of decades prior.
But while the German carmaker’s 300 SL Gullwing featured the signature avian-looking doors because it was built on a tubular chassis, Boschert added them to his B300 car for aesthetic reasons. That explains the structural changes to the body and the additional strengthening of the sills that was necessary after cutting out the B-pillar. The doors are operated electronically by means of a hydraulic pump, which also allows the driver to adjust the ride height.
Besides the amazing design, the Boschert B300 Gullwing impresses with its performance capabilities. The custom car is powered by a sequential twin turbocharged Mercedes-Benz M103 3.0-liter engine producing 283 hp and 220 lb-ft of torque sent to the rear wheels through a five-speed manual transmission. Besides the two Garrett turbos bolted onto the engine, Boschert also added a Mosselmann cooling system and an all-new exhaust system.
The car is said to accelerate from 0 to 60 mph (0 to 97 kph) in under 6 seconds and be capable of reaching a top speed of around 165 mph (266 kph).
As mentioned, Boschert’s initial plan of a 300-unit production run was way too optimistic. Despite the fact that the B300 elicited a positive response from the automotive world, he only received ten orders for the car, but all of them were for the model with conventional side-opening doors. As a result, the original Boschert B300 displayed at the 1989 IAA in Frankfurt remained the only unit built with gullwing doors. One factor that led to the low demand was the whopping price tag of DM 186,000 (Deutsche Mark), which was enough to buy a nice house back then. But then again, exclusivity doesn’t come cheap.
The Boschert B300 Gullwing has been in private hands since 2005, when an enthusiast by the name of Tino Zovko discovered it on eBay. The man spent a lot of time and money on returning the car to its original condition and is now putting it up for auction with a price guide of $265,000 – $320,000 USD.
While the original Mercedes-Benz 300 CE it is based on was finished in Astral Silver over a black interior, the custom vehicle’s exterior was refinished in Bornite in 1990, and the interior received two-tone purple leather upholstery. According to the listing, the car benefitted from €16,216 ($17,305) worth of repairs earlier this year, and a further €4,771 ($5,091) was spent on paintwork, upholstery, and interior fettling.