What Car? says...
BMW supplies its cars to both its motorsport division M Sport and tuning house Alpina, but what results from each organisation is very different.
It’s best to think of M cars as hardcore, track-focused models that are hell-bent on lapping racetracks as quickly as possible. Alpina, on the other hand, is about long-legged performance, long-distance comfort and sumptuous luxury. It’s a tracksuit and trainers versus sports jacket and brogues situation.
The B4 S is Alpina’s take on the BMW 4 Series, but it is closer to the range-topping M4 in terms of performance. In fact, it has more power than that car – although the B4 S is fitted with the same basic 3.0-litre six-cylinder petrol engine, it has undergone some unique revisions by Alpina to produce more oomph. It’s available as either a coupé or convertible; it’s the coupé we’ve driven and are focusing on here.