GREER, South Carolina – With the latest-generation X3 already the segment’s kingpin in terms of dynamic handling, how the X4 could improve that benchmark was always going to be the question levelled at this more svelte sibling. And more svelte it certainly is, with added definition in its sculpted flanks and shoulders, slimmer rear lamps and BMW’s amplified interpretation of its kidney grille. While coupé-like SUVs do remain the niche of a very particular automotive taste, this new X4 does look significantly more resolved and comfortable in its skin than its slightly awkward forbear.

Like the X3 and the 5 Series, it is based on BMW’s new (larger but lighter) CLAR platform. It’s therefore a bigger car than the one it replaces – 81 mm longer, 37 mm wider and a 54 mm longer in its wheelbase – with noticeably more interior room. Still, the overall packaging is not as generous as that of the X3, with less headroom aft, as well as decreased legroom across the second row. Its boot is also smaller than the X3 at 525 litres, but that’s still a size large enough for average family duties.

Compared with the outgoing X4, the CLAR platform brings with it a wider track, lower centre of gravity, up to 50 kg less mass and 10% less aerodynamic drag than its predecessor. Added to the obvious dynamic qualities these changes bring – well documented in our tests of both the X3 and 5 Series – the M40d also sports trick chassis components and an uprated engine. The dynamic traction system works through the M Sport differential to apportion the requisite grip fore and aft, while the X3 suspension has been adjusted to suit the X4’s lower centre of gravity, with a standard-spec adaptive M Sport suspension, Performance Control torque-vectoring system and variable sport steering fitted to all models. The M40d also benefits from M Sport brakes.

Under the hood is BMW’s excellent 3,0-litre, straight-six turbodiesel found in a number of the marque’s current range, though here it’s tuned up to deliver an Audi SQ5-rivalling 240 kW and 680 N.m of torque to all four wheels, with a slight bias to the rear. It’s a drivetrain we were able to put to the test on a circuit at BMW Performance Centre’s proving grounds in Greer, South Carolina (where the vehicle is built). The bumped-up engine remains a gem and a personal favourite, although in manual mode I often found myself hitting the limiter sooner than I expected as the diesel taps out at 4 500 r/min, which means you tend to move through the gears fairly quickly. There’s little lag, response is excellent and the in-gear punch ferocious enough to make it feel like a performance vehicle.

Cycling through the different stages of traction control while lapping the small track served to highlight just how engaging the X4’s handling can be in any mode. Typically of a BMW, thanks to the adaptive suspension and steering system, the crossover provides an accurate and responsive feel granting you enough confidence to push it to the edge. There the vehicle defaults to safe understeer, but it’s possible to bring the rear-end in to play by lifting the throttle.

Realistically, though, very few X4s will spend time on a racetrack and its day-to-day manners as a crossover are far more relevant. On the road, the X4 remains a composed and comfortable vehicle. In comfort mode, engine, road and wind suppression are impressively low and the adaptive suspension provides a well-damped ride, negating the harshness of the low-profile 20-inch alloy wheels on the roads of South Carolina. The turbodiesel also provides a smooth delivery of power to the four wheels and offers equally slick gear changes via the eight-speed torque converter.

As ever, the X4 remains a niche product, designed to appeal to those who want a blend of sporty coupé-like styling with more practicality than actual two-door variants can offer. This mix does come at a price, however, and the less-expensive X3 M40i, for example, offers only marginally less in terms of dynamic abilities but better packaging (and you can order your X3 M40i with the adaptive M suspension as an R11 000 option).

When it launches here in September 2018, the X4 range will comprise the 20i, 20d and M40i, with this M40d making its appearance in the first quarter of 2019. There’s no indication of its pricing yet but, with the X4 M40i costing R1 148 185 at launch, we can expect the oil burner to be in the same ballpark. For those who still find 240 kW a little lacking in punch, you might want to hold on for a while longer as BMW unveils the X4 M in 2019.