What is it?
At its heart, this is a more powerful Alpina B4, available as a coupé or convertible and as a B3 S with saloon or Touring bodywork.
For a tuning house keen to make clear that its job is not to tread on the toes of BMW’s M Division, the figures make for interesting reading.
But before that, a quick look as what’s been done. These new S models are not additional to the B3 and B4 range, but replace them. That said, the chassis has been left unchanged - because Alpina says it didn’t need changing - so what we’re looking at here essentially is a powertrain job.
As before, the host unit is BMW’s N55 motor but with its block recast to accept Alpina’s twin-turbo application. It has a forged steel crank, 10% bigger turbos, 20% more cooling capacity for the water and 35% more capacity for the oil. And again, the sound of the motor is spat out through Akrapovič exhausts. The automatic transmission is strengthened, has a bigger step between Drive and Sport modes and offers quicker shifts.
This work raises power by 30bhp to 434bhp and torque by more than 10% up to 486lb ft. So, Alpina’s hot 3 Series and 4 Series-based models are now more powerful than BMW M’s equivalent propositions, and offer a stack more torque. Yes, the M cars are lighter (78kg for a two-pedal M4), which means they just manage to hold a fractional power-to-weight ratio advantage, but in terms of the arguably more important torque-to-weight ratio, the Alpinas are a distance ahead. The Alpina is more expensive, but by less than £2000. It should also be mentioned here that while the Alpinas are automatic-only, unlike their M car equivalents, they are available with rear or four-wheel drive.
The unchanged chassis retains Alpina springs, dampers and bars and comes with additional front camber relative to the M3 and M4.
What's it like?
Forget that the figures point to a mere 0.1sec improvement in 0-62mph time, as traction limitations render such news worse than meaningless. Whereas the B4 always felt undeniably rapid, the rear-wheel-drive B4 S coupé we're driving here is a serious high-performance machine.
And it’s not difficult to see why: it’s not the power but that additional torque in the middle of the rev range that provides real-world performance a clear step ahead of its predecessor. The motor’s throttle response is almost as good as a normally aspirated unit and its unadulterated sound is actually better than most.
I had feared this extra grunt might ask questions the unchanged chassis would struggle to answer, but, on the track at least (which was the only place I was allowed to drive it), it did just fine. It’s a softer car than the M4 and there’s a price to be paid in body control through very fast corners and over undulations, but it never feels nervous, as an M4 can, and instead of skidding suddenly when power overwhelms grip at the back, it slides beautifully. I expect its lap time would still lag some distance behind that of the M4, but it would be interesting the measure the width of the smiles on each driver’s face at the end of a stint.
Should I buy one?
The M4 is a quicker, more exciting car than the B4 S, although not necessarily for all the right reasons. In the traditional Alpina way, the B4 S is more subtle, considered and aimed at those who don’t want to trumpet their arrival too much.
A while back, we drove a B4 alongside an M4 and considered the Alpina the far more rewarding and satisfying driver’s car, not to mention being somewhat easier to live with. I can see no reason why the more punchy B4 S would not do at least as well in the same comparison, probably better.
Even just seen as a car its own right, the B4 S has a character you don’t find elsewhere. So forget the comparisons, and focus instead on the fact that this is a car of real class and charm. What’s more, with Alpina only selling around 150 cars of all kinds in the UK each year, if you bought one, the chances of seeing another like yours would be almost nil.
Alpina B4 S
Where Bilster Berg, Germany; On sale Now Price £63,000 Engine 2993cc, 6cyls, petrol; Power 434bhp at 5500rpm; Torque 486lb ft at 3000rpm; Gearbox 8-spd automatic; Kerbweight 1690kg; Top speed 190mph; 0-60mph 4.2sec; Fuel economy 35.8mpg; CO2 rating 180g/km; Rivals BMW M4, Mercedes-AMG C63