The third-generation BMW Z4 has reached the final phase of development ahead of a planned public debut for the new two-seater at the Pebble Beach Concourse D’Elegance in Monterey, USA, in August.
Known under the internal BMW codename G29 and designed by Australian Calvin Luk, the 2019-model-year roadster has been engineered anew from the ground up with a significantly more contemporary platform and, according to the German car maker, with more sporting handling traits than the second-generation model it replaces – the so-called E89 introduced to the BMW line-up in 2009.
With less than three months until its world premiere, BMW indicates the engineering focus on the new Z4 has switched from all-out durability testing to more detailed fine-tuning of its chassis. Much of the final development, it says, has taken place at the company’s Miramas test track in southern France, where future models can be tested away from the glare of the public on a variety of different test tracks.
Previewed in concept car guise at last year’s Pebble Beach Concourse (above), the new Z4 is larger than the third-generation Z4, with wider tracks providing it with a more confident stance.
“A shorter bonnet and crisp overhangs ensure the driver sits closer to the centre of the car than in previous BMW roadsters,” says BMW design boss, Adrian van Hooydonk.
The new BMW Z4 shares key elements of its platform, inner body structure, chassis and electrical architecture with the revived Toyota Supra – itself due to make its public premiere at the Detroit motor show next January. But while the Z4 sports the folding fabric roof structure worn by the prototypes shown here, the new Supra will be sold exclusively as a fixed roof coupe.
Replacing the folding hardtop arrangement of its predecessor, the new Z4’s fabric roof is claimed to open and close in just 10sec up to speeds of 50km/h. When the roof is stowed behind the cabin, the new roadster offers up to 228 litres of luggage capacity – some 48 litres more than the model it replaces, according to BMW sources.
The Z4 and Supra, which will be produced together at automotive production specialist Magna at facilities in Graz, Austria, will also share drivelines, with the Toyota set to adopt specially tuned versions of BMW’s in-line four- and six-cylinder engines and ZF-engineered eight-speed torque converter equipped automatic gearbox.
BMW has only revealed limited details to its new roadster ahead of its world debut. However, it confirms the new Z4 line-up will be headed by a range-topping Z4 M40i M-Performance model. It is expected to receive the same turbocharged 3.0-litre in-line six-cylinder petrol engine as that used by the X3 M40i. With 265kW at 5500rpm and 500Nm of torque, it promises to endow the new open top with the sort of straight-line performance to challenge the likes of the Porsche Boxster S, which runs a turbocharged 2.5-litre horizontally-opposed four-cylinder engine with 257kW at 6500rpm and 420Nm at 1900rpm.
To put the power to the ground, the rear-wheel drive Z4 M40i has the same rear axle as the M3, with an electronically controlled differential. In the top-of-the-line Z4 model, it is allied to a standard eight-speed automatic gearbox.
Other engines likely to be offered include a turbocharged 2.0-litre petrol engine. It is expected to develop 135kW and 290Nm in an entry level Z4 sDrive20i model and 185kW and 250Nm in the planned mid-range Z4 sDrive30i – both of which are expected to come with the choice of either a standard six-speed manual or optional eight-speed automatic gearbox.
BMW says it has conceived the new Z4 as a more driver orientated model than its predecessor.
“The whole concept behind the new car is geared more towards agility and driving dynamics,” explains Jos van As, head of chassis development, adding, “Increased rigidity and a very stiff connection between the chassis and body structure offer ideal conditions for tuning.”
In a bid to heighten the handling qualities of the Z4, BMW says it has provided the range-topping M40i model with a lowered sports suspension featuring adaptive damping control, a newly developed front axle, different sized wheels and tyres front and rear, an M-Sport brake package. Together, BMW claims they help provide the new roadster with “new standards of driving enjoyment in the roadster segment”.
Independent judgement on just how much better the 2019 iteration of the Z4 is than its 10-year-old predecessor will have to wait until we get to drive it later this year.