Order a standard 4 Series and you get BMW's standard suspension. But if you order an M Sport-spec car, you get M Sport suspension, which includes firmer dampers, springs and anti-roll bars.
You can also order M Sport suspension on non-M Sport-spec models. Or on all models you can specify adaptive suspension, which brings electronically controlled dampers with two modes of stiffness
They’re complemented by an additional Eco Pro mode on the softer setting, which maximises fuel economy, and Sport+ mode on the firmer setting, which reduces the level of intervention by the electronic driver aids.
Compared with an equivalent 3 Series saloon, the 4 Series wears its added athleticism quite casually. Those equipped with BMW’s adaptive dampers and M Sport alloys and suspension settings are at their most pleasing in Comfort mode. In it, there’s enough compliance in the suspension to deal with back roads tackled with plenty of gusto.
You can tell, now and again, that some of the bump-accommodating wheel travel of the 3 Series has been sacrificed, but only over really bad roads, where the dampers seem to need an extra stroke of movement to do their work. Most of the time, the 4 Series flows over flatter surfaces with sporting readiness but also an unwearing sense of calm that makes it feel dynamically versatile.
Sport mode dials some of the vertical movement out of the ride, but at the cost of permitting a touch of harshness into the cabin over the same bad surfaces, which isn’t worth the compromise. Nevertheless, the adaptive M Sport suspension is definitely an option to have.
In either setting, the 4 Series steers precisely, with plenty of grip and a low rate of roll. It’s a meaty, precise machine to thread along an A-road at speed, just as it is a relaxed one on the motorway.
It could be more lively, more ‘sporting’, granted. On the margins, handling is a bit more stability-biased than we expected, but experience suggests that’s as much to do with the wide M Sport wheels and tyres as anything. We'd expect the more typical Sport-spec car to have slightly better limit cornering balance and, in the UK, to probably make a marginally more rewarding drive – as paradoxical as that may sound.
One option to avoid is the Variable Sport Steering, which dials the BMW 4 Series’ rack down to just 2.2 turns between locks, but relies on greater power assistance to keep the effort levels sensible. You get a less feelsome, less predictable steering rack on your 4 Series if you go for it – albeit one that masks understeer quite effectively at normal speeds.
