The Alpina B3 S and B4 S Biturbo models have been revealed at Geneva with more powerful 3.0-litre straight-six engines that produce 434bhp and 443lb ft of torque. The B4 S will also be launched at the London motor show next week.
That gives the models 9bhp and 37lb ft more output than BMW’s M3 and M4 models, and enables the B4 S to accelerate from 0-62mph in 4.2sec, with the B3 S taking a tenth longer. Top speed for both models is 190mph.
The extra performance comes thanks to two new Alpina turbochargers and a new high-performance cooling system with an external water cooler and external oil cooler which have grown in capacity by more than 15 % and 35 % respectively.
The new system helps torque arrive at 2000rpm; it remains at peak output until 6000rpm. The engine comes mated to a ZF eight-speed automatic gearbox in both variants, and breathes through an Akrapovič stainless steel exhaust system that weighs less than BMW’s equivalent.
The B3 S and B4 S come in rear or all-wheel drive forms. The B3 S is available in saloon and Touring guises; the B4 S comes in coupé or convertible bodystyles.