What may seem like a fairly standard BMW 1 Series Convertible from the E88 era is a true beast once you get closer to the car and notice the M3 E90-styled hood. Pop it open and this 118i’s original N43 2.0-liter inline-four engine is no more. Instead, whoever built this sleeper car opted to cram in a V8, specifically an S65 from the M3 E90. Rather surprisingly, it fits in there quite nicely and almost looks like it was installed from the factory.

Aside from the engine transplant, the droptop 1er has borrowed the front and rear subframes from an M3 E92. It rides on 19-inch M Performance wheels with Michelin Pilot Sport Cup 2 tires and StopTech brakes. Hilariously, the original 118i at the back is still there, along with a quad exhaust system letting everyone know it’s not a regular 1 Series. At the front, there’s an E92-esque bumper.

It wouldn’t be a complete project without a proper manual gearbox and this uses a six-speed from an E90 M3. The interior has been discreetly modified to include some M upgrades such as the steering wheel and instrument cluster. There’s also a button between the gear lever and cup holders to adjust the three-stage KW dampers.

With 420 horsepower and 400 Newton-meters (295 pound-feet) of torque in a rear-wheel-drive car that weighs 1,620 kilograms (3,571 pounds), it’s safe to say this 1 Series Convertible is a real hoot to drive. It is substantially heavier than the standard 118i due to the much larger V8 engine, but the extra bulk should be offset by the massive power gains.

The car has only covered 1,000 kilometers (621 miles) with the new engine and it’s fairly easy to notice its tail-happy nature. Interestingly, the owner originally built this car for his wife but now it’s already for sale. AutoTopNL did the standard procedure of driving it to the maximum on the Autobahn, but the top speed run ended suddenly at 270 km/h (168 mph) when some parts of the underbody started to fly off.

If you’re curious how much it costs, this V8-powered 1 Series Convertible is listed on a Dutch website for €38,450.

Source: AutoTopNL / YouTube, AutoServiceProCar.nl