Anyone who wants a four-seat Mercedes SL can buy this Boschert B300 Gullwing. It is a one-off model built on the basis of the Mercedes 300 CE (W124) and will be offered for sale at a Broad Arrow auction taking place on May 16 at Lake Como, during the Villa d’Este Concours d’Elegance. The estimated price is around half a million euros.
Presented at the Frankfurt Motor Show in September 1989, the Boschert B300 Gullwing is a unique example based on a Mercedes 300 CE (W124), transformed with gullwing doors like those of the famous 300 SL from 1954 (W198), and featuring the front end of the then-new SL (R129).
The B300 Gullwing is one of the most spectacular conversions of its time. Designer Hartmut Boschert shortened both the roof and the rear section of the 300 CE by 25 cm, giving the coupe a more dynamic silhouette. However, the most striking modification is the gullwing doors, 1.66 meters wide, which on the B300 are operated electro-hydraulically. The front end stands out with headlights taken from the SL R129, while the front fenders were custom-made.
The front seats were also borrowed from the SL R129. The gullwing doors open hydraulically, and their closing is assisted by a soft-close mechanism taken from the W124 T-Model. Although there is no B-pillar, the torsional rigidity is higher than that of the standard 300 CE coupe, which also lacked a central pillar.
Under the hood is the Mercedes M103 3.0-liter inline six-cylinder engine, originally producing 188 HP. However, it was modified by Dutch tuner Mosselman, which installed two turbochargers and an intercooler, increasing power to 283 HP.
This is not a conventional twin-turbo setup with one turbo per three cylinders. Instead, the turbos are arranged in series: a smaller, low-inertia turbo to minimize lag, and a larger one for higher engine speeds.
As in the 300 CE, the turbocharged engine sends power to the rear wheels through a 5-speed manual gearbox, with a top speed of 258 km/h.
Boschert planned to produce a limited series of 300 units, at a rate of three per week. A four-valve-per-cylinder version of the M103 (which originally had two valves per cylinder) was also planned. However, only 10 examples with conventional doors were built, making this gullwing version a true one-off.
At the time, this example was priced at 186,000 Deutsche Marks, meaning it cost more than double compared to the 300 CE W124 it was based on, and was also 50,000 DM more expensive than the Mercedes 500 SL R129.
After its Frankfurt debut, the Boschert B300 initially remained in Germany before being acquired by engineer Tino Zovko, who had admired the model since childhood. Impressed by his enthusiasm, Boschert agreed to meet him and provided the car’s original documentation.
The B300 remained in Zovko’s possession for over 20 years before being sold in November 2023 to its current owner. Prior to the sale, Zovko fully restored the car at a cost exceeding €20,000, including repainting and new upholstery.
The car was sold at a Sotheby’s auction in Munich in November 2023 for an extraordinary €455,000, far above the initial estimate of €250,000–300,000. It now has just over 39,000 km on the odometer, and its current estimated sale price is between €475,000 and €525,000.
The car’s excellent condition and exclusivity—being the only gullwing example—justify a price slightly higher than that of a Mercedes 190 Evo II.
