Based on the BMW 4 Series, the B4 and D4 are manufactured in coupé and convertible body styles.

The N55 straight-six engine was modified by using twin-turbochargers, a 61 percent larger intercooler and a new crankshaft.

[2] The B4 has adjustable dampers that can be calibrated to provide a softer compression but firmer rebound.

[3] The car has a Brembo braking system with 370 mm (14.6 in) front and 345 mm (13.6 in) rear brake discs working in conjunction with four piston callipers at the front and two piston callipers at the rear.

[4] The interior has Lavalina leather upholstery, which can be tailored to customer specifications,[5] and sports adjustable seats, a hand-stitched steering wheel and new door sills.

Based on the 435d, the N57 turbo diesel inline-6 engine found in the donor car was slightly modified by adding two small variable geometry turbochargers and a new intercooler.

On the interior, burled Elm wood trim, adjustable heated front seats, dual zone climate control and Dakota leather trim are standard equipment.

A heads-up display and an array of choices for the upholstery and trim are optional.

Two new color options are available for the exterior, those being Fire Orange and Grigio Medio with black accents.

The car is available with 20-inch classic Alpina multi-spoke alloy wheels in Ferric Gray finish.

The interior features piano black lacquer trim with "Edition" lettering, new sports seats, the shift paddles finished in matte black and a stainless steel plaque signifying the production number of the car out of the 99 units produced.

The ZF eight-speed transmission has been reinforced, the sports chassis is specially connected and has weight-optimized components, and its own stabilizers on the front axle.

The B4 Gran Coupé is said to accelerate to 100 km/h in 3.7 seconds, and the manufacturer states the top speed as 301 km/h.