A byword in the tuning industry, German tuner AC Schnitzer built a one-off roadster that encapsulates its design capabilities and engineering prowess with the ACZ4 5.0d. The base car is a run-of-the-mill BMW Z4 231 sDrive that has been modified from the ground up.
The core of this heavily-modified Bavarian beast starts with the engine, as AC Schnitzer swapped the stock engine with a more powerful M50d power plant from a BMW 5-Series. Schnitzer upgraded the engine with go-fast goodies and bolted it on the ACZ4 5.0d. The car now screams with a 316 kW/430 hp motor and has a maximum torque of 840 Nm.
To cope with the engine power, the rear axle gear and limited slip differential from a BMW M3 (E92) replaced the standard rear differential, and the standard manual gearbox has been replaced with an 8-speed automatic with pedal sports shift. With enough grunt under the hood to make any car enthusiasts salivate with desire, this metal beast on wheels sprints from 0 to 100 kph in an incredible 4.5 seconds, and reaches its top speed beyond the 300 kph mark at 1:37.22 minutes. It is by far, the fastest diesel roadster to run at the Sachsenring.
The increased engine output would not have pushed the power curve of the ACZ4 5.0d, so engineers had to factor into the equation a systematically applied lightweight construction, like the electro-hydraulic metal folding roof and the rear deck lid have being replaced by CFC constructions. These optimizations account for a 90-kg weight reduction. The standard silencer has been replaced by a lightweight silencer, so now the exhaust doesn’t add 23-kg ballast, but just 4 kgs.
A further 25 kg of weight was removed with the wheel set with AC Schnitzer forged alloys Type VIII, which combines rims in 9.5J x 19 inch with tires size 265/30 R19. As a whole, with a few further measures, 131 kg has been “trimmed off” so despite the significantly heavier M50d power plant, the car weighs in at just 1,469 kg.
Aside from the engine modifications, a custom-made instrument console was crucial to the one-off build. A peek into interior of the AC Schnitzer ACZ4 5.0d says a lot about this special car: interior trim elements in orange, and carbon racing bucket seats offering strong lateral support, with the embroidered ACZ4 5.0d logo, were all specially made. Aluminium pedals and foot rests, and velour floor mats complete the interior package of the car.
To control the raw power of the ACZ4, Schnitzer optimized the overall performance of the car by adopting their power-to-weight formula. The racing suspension are fully adjustable in both compression and rebound stages, and the low stance of the Z4 bodywork combined with the lightweight high performance braking system on the front axle ensures excellent and stable acceleration and deceleration.
The 30-mm lowered body in conjunction with the AC Schnitzer aerodynamic components gives a further perceptible reduction in drag. The aerodynamic conversion, which naturally also significantly defines the looks of the ACZ4 5.0d, consists of a carbon front spoiler, two carbon sports fenders, two bonnet vents, a two-piece rear spoiler and the carbon rear skirt insert that perfectly integrates the rear silencer.
The AC Schnitzer ACZ4 5.0d concept vehicle will not go into production. It was initially produced to customer specifications and at the same time acted as a technology platform for AC Schnitzer product development. In its current form, the vehicle would cost € 113,965.