Buchloe-based tuner Alpina has shown off its upcoming B4 S Grand Coupé at the Goodwood Festival of Speed.
They arrive shortly after Alpina brand was acquired by BMW and thus are officially named the BMW Alpina B4 S and BMW Alpina D4 S.
They're expected to be the final additions to the marque's current-generation line-up of modified BMW models.
As with Buchloe'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.
The D4 gets the same gearbox, but is equipped with a 3.0-litre mild-hybrid straight-six diesel powerplant pumping out 350bhp but matching the petrol car’s 538lb ft.
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 D4 adds another 55kg and needs 4.8sec to get to 62mph from rest.
The B4 manages 28mpg on the WLTP cycle and emits 229g/km of CO2, while the D4 hits 40.9mpg and emits 182g/km.
Modifications to the gearbox include reinforcements, 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.