Renowned tuning firm’s new B4 Gran Coupé brings 488bhp and a whopping 568lb ft of torque
It’s expected to be the final addition to the marque’s current-generation line-up of modified BMW models.
As with the firm’s take on the BMW 3 Series, the Alpina B3, the new B4 uses a tuned version of the ‘S58′ twin-turbocharged 3.0-litre straight-six petrol engine, sending 488bhp and 538lb ft through an eight-speed automatic gearbox to both axles – only slightly less power and 59lb ft more torque than the 503bhp M4 Competition.
Despite the power deficit and weighing 240kg more than the two-door M4 Competition, the B4 is actually 0.1sec quicker than the more hardcore car from 0-62mph, needing just 3.7sec for the sprint, and it just pips it for top speed, too, topping out at 187mph.
The B4 manages 28mpg on the WLTP cycle and emits 229g/km of CO2.
Modifications to the engine include bespoke turbine housings that “convert exhaust gas energy into boost pressure” at low engine speeds, a larger intercooler, an upsised air filter system and an optimised cooling system.
The gearbox has been reinforced, too, to cope with the substantially boosted torque output and is configured to send the bulk of the engine’s power rearwards, “as befits the athletic character” of the car.
Unlike the M4, the B4 is geared towards providing not only “high-level driving dynamics but also lots of comfort for relaxed touring”. The chassis has therefore been extensively modified in keeping with this billing.
Alpina lists upgrades including new bulkhead reinforcement struts, stiffer bushings and mounts, bespoke front anti-roll bars and a unique spring-and-damper configuration among the hardware changes that give the B4 a distinct character. Variable dampers are said to give “noticeable differentiation between the various driving modes”, while three different modes of steering response are available.
The brakes have been upgraded, too, with four-piston callipers gripping 395mm discs at the front and floating callipers paired with 345mm discs at the rear. Drilled, lightweight composite discs are optionally available.
As is customary for an Alpina car, the styling differences over the standard 4 Series are much more subtle than those of the M4. Unique bumpers, spoilers, exhaust exits, side skirts and badging are the obvious tells, plus there’s a new interpretation of the brand’s hallmark 20-spoke alloy wheel design.
Alpina says a new manufacturing process means these 20in wheels tip the scales at just 12kg each.
They’re wrapped in high-performance Pirelli P-Zero tyres designed especially for Alpina.
The B4 is now available to order ahead of deliveries getting underway in July, priced from £80,663.