BMW has renewed its challenge to the Porsche Boxster with the Munich-based firm's new (and thoroughly repackaged) Z4 roadster… Our Irish correspondent Shane O' Donoghue drove the M40i range-topper in Portugal.

BMW sniffs an opportunity for its 3rd-generation Z4 roadster. In its reinvention, specifically in M40i range-topping guise, it could well plug the gaping hole in 6-cylinder roadster enthusiasts’ lives left by the demise of the flat-6Porsche Boxster and Cayman. Yeah, we know there are boosted V6 versions of the Jaguar F-Type and Mercedes SLK, but those cars can’t hold a candle to the latest Porsche 718's chassis. Can the Z4’s? BMW certainly thinks so.

What's changed?

The old hard-top roof has been replaced with a lighter, canvas roof.

The previous Z4 was a soft pudding of a car, but you get the sense that the engineers in the company were given more of a say this time around. The new model is 85 mmlonger, 74 mm wider and 13 mm taller; while the front and rear tracks have been increased by 98- and 57 mm respectively. So far, nothing too unusual, but then you’re told that the wheelbase has been shortened, giving the Z4 an all-square stance on the road, with the chassis team’s eyes firmly set on the centre of the target marked "agility".

To make the most of the layout, BMW focused on the rigidity of the body, creating the stiffest structure of any open-topped car it has yet produced. On top of that, the hefty high-mounted folding hardtop of the previous Z4 was binned, in favour of a light new fabric roof. That not only reduces overall weight, it also helps bring the centre of gravity down and, as a side benefit, it neatly folds away (at speeds of up to 50 kph) in front of a much-enlarged boot space (in just 10 seconds).

The new Z4 has its sights squarely on the Porsche Boxster.

The fabric roof is black as standard andoptionally available in Anthracite Silver. The latter works particularly well on the Z4 M40i, which gets the usual Cerium Grey details found on a BMW M Performance Vehicle– though they’re admittedly lost when put up against the Frozen Grey paintwork of the test car. Still, your eyes will be too busy digesting the weird new kidney grille mesh up front and the protruding aerodynamic breathers behind the front wheels to worry about trim colours, though we reckon there’ll be universal approval for the muscular rear end and high-tech LED lights. The keen-eyed will note there are mixed tyre sizes front and rear, which is the case across the whole Z4 line-up – and again reinforces our sense that the engineers were listened to for this car’s development.

Better oily bits

There’s more technical goodness underneath as standard in the M40i, including Adaptive M Sport suspension with electronically controlled dampers, M Sport brakes and, perhaps most importantly of all, an M Sport differential on the rear axle. Naturally, all Z4s send their power to the rear wheels, exclusively through the latest development of BMW’s excellent 8-speed Steptronic automatic transmission.

Interior features a much larger centre screen and new iDrive controller.

This comes with tactile gearchange paddles behind a high-quality three-spoke M-branded steering wheel in the M40i. There’s a lot more going on in the cabin for you to check out, including a new dual-screen dashboard called BMW Live Professional. In front of the driver are digitally rendered instruments that change appearance depending on driving mode, while the central touchscreen uses a brand-new operating system and interface.

It’s super-quick to use by touch, though we reckon it’s still easier to use the newly-styled iDrive rotary controller to navigate the menus when you’re on the move. The rest of the cabin is neatly styled and beautifully put together. You sit down low as you’d hope, with plenty of adjustment in the seats and steering wheel. There are plenty of small storage areas and don’t forget to fit the (rather flimsy) plastic wind deflector between the roll hoops behind before you attempt any speeds higher than the urban crawl.

Gutsy straight-6

The straight-6under the long bonnet puts out 250 kW and 500 Nm of torque.

And while the new Z4 is perfectly civil with its multi-layer roof in place, you buy a roadster to drive it with the wind in your hair, right? What’s more, you’ll want to do that to let your ears have unhindered access to the exhaust note. It’s a sonorous tune that only a straight-six could sing, even a turbocharged one. There’s 250 kW of power from 5 000 to6 500 rpm and this engine really does encourage you to go looking for it all with a purposeful, yet cultured snarl, with the soft limiter kicking in at7 000 rpm. Not that you actually ever need to use that many revs, becausethere’s a chunky 500 Nm of torque produced from 1 600 to 4 500 rpm, making the M40i feel rapid seemingly regardless of engine speed or gear selected.

That’s especially the case if you choose Sport or Sport+ driving modes, as everything sharpens up noticeably, banishing memories of the previous Z4 to history. The Sport+ setting is particularly aggressive in terms of throttle response and gear selection. The best news though is that the adaptive damping never turns the car into a denture-loosening mess; sure, it ramps up the firmness and body control in the Sport modes, but not at the expense of composure over rougher surfaces. This means you can still use the Z4’s performance to the full, even when not on a glass-smooth road. In Comfort mode it’s surprisingly relaxed, too, making for a good long-distance cruiser.

Is it a proper sportscar?

BMW has shortened the wheelbase on the Z4 to make it more agile while widening the track for better traction.

Last, but certainly not least, is that M Sport differential, a fully active unit, the operation of which is mapped to the driving modes. In Comfort mode, this attempts to keep the rear of the car stable at all times, while enhancing traction. It does that to a certain extent, though even so, if you’re clumsy with the throttle on the exit of a dusty or damp junction, there’s a momentary reartwitch to serve as a reminder of which end the power is being sent.

On the move, it’s never nervous, however, and it takes a little provocation to push beyond that initial movement, especially on dry tarmac. The differential allows for a more "dynamic" stance on the exit of corners if you’re in one of the Sport modes, as you’d hope, and this reveals a delicious balance to the whole car.

You can really lean on the outside tyres and get on the power incredibly early, letting the differential do its thing. What’s more, on the approach to a corner and on initial turn-in, it can also help make the Z4 feel "pointy", adding to the overall sense of agility. No doubt the sports steering adds to that, as it’s a variable assistance and ratio system. Feedback to your hands isn’t bad, though would be better with a thinner steering wheel rim. The brake pedal is reassuringly firm, even after a spirited mountain drive, allowing you to confidently deployas much braking force as you need.

Summary

Confidence is a word we’d use to summarise the new BMW Z4 M40i. This is an incredibly polished product from the German marque, mixing quality with the latest interior technology and the usual desirability of a drop-top roadster with rear-wheel drive. BMW has managed to incorporate all of that while giving its new Z4 a chassis that is clearly developed with the enthusiast in mind… especially so in the M40i. So, do you still want that Boxster?

A local BMW representative has confirmed that the new Z4 will reach South Africa in Q1 2019.

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