BMW Reveals 8-Series Soft-Top, Readies New M8

BMW reveals the new 8-Series convertible ahead of the new 2-door’s public debut later this month at the Los Angeles auto show.

Meanwhile, lightly disguised prototypes of BMW’s M performance-car division’s upcoming M8 flagship (below, left) have hit the racetrack as engineers fine-tune its chassis and driver-assistance systems in the latest round of testing for the luxuriously equipped 2-door.

Conceived to rival existing upmarket convertibles including the latest Bentley Continental GTC and Mercedes-Benz S-Class cabriolet, the new BMW open-top forms part of a resurrected 8-Series lineup that also includes the recently introduced 8-Series coupe and the upcoming 4-door 8-Series GranCoupe set to be unveiled later next year.

The indirect replacement for the earlier 6-Series convertible is planned for North American delivery in March, according to BMW.

Predictably, the new 8-Series convertible mirrors the look of the new 8-Series coupe, with a bold front end and muscular lines.

BMW claims an overall 12.4 cu.-ft. (351 L) of trunk space with the roof in place, though this is reduced when it is stowed. To accommodate lengthy items, the rear seats split and fold in a 50:50 configuration to free up load space.

The 8-Series convertible will be sold from the outset of European sales in March with the choice of two engines: a turbocharged 3.0L inline 6-cyl. diesel making 316 hp and 502 lb.-ft. (681 Nm) of torque at 1,750 rpm in the 840d xDrive convertible, and a turbocharged 4.4L V-8 gasoline delivering 523 hp and 552 lb.-ft. (748 Nm) of torque at 1,800 rpm in the initial range-topping M850i xDrive convertible.

Both engines come mated to a standard 8-speed torque converter-equipped automatic gearbox and BMW’s 4-wheel-drive xDrive system. The M850i xDrive convertible also receives an electronically controlled rear differential lock, which is optional on the 840d xDrive convertible.

BMW claims the 4,310-lb. (1,956-kg) 840d xDrive convertible accelerates from 0-62 mph (100 km/h) in 5.2 seconds and hits a top speed limited to 155 mph (250 km/h) while delivering combined-cycle fuel consumption of 46.1 mpg (5.1 L/100 km).

Despite weighing 132 lbs. (60 kg) more than its diesel sibling at 4,442 lbs. (2,017 kg), the M850i xDrive convertible is claimed to run to 62 mph in just 3.9 seconds and reach the same limited 155-mph top speed while returning similarly adjusted combined cycle fuel consumption of 31.4 mpg (7.5 L/100 km).

Details pertaining to the U.S. lineup are yet to be revealed.

The M8 coupe is aimed at rivaling the likes of the Bentley Continental GT Speed, Porsche Panamera Turbo and Aston Martin DB11 at a price of about $150,000 in North America. The new 4-wheel-drive model has entered a final phase of development ahead of a planned public debut next September at the Frankfurt auto show.

The M8, which will crown the newly resurrected 8-Series lineup, will be sold with the choice of three different body styles. The first to reach U.K. showrooms will be the M8 coupe undergoing testing earlier this month at the Estoril circuit in Portugal.

It will be followed by an M8 convertible set for launch during the latter half of 2019, with a 4-door M8 GranCoupe also confirmed for launch during first-half 2020.

The M8 is powered by the same gasoline V-8 as the M5. As with the engine in its 4-door sibling, the longitudinally mounted twin-turbocharged 4.4L unit will be offered in two different states of tune.

In standard M8 guise, the 90-degree engine will be tuned to deliver more than 600 hp, according to BMW M development boss Dirk Häcker. By comparison, the current range-topping 8-Series model, the M850i xDrive, runs a less heavily tuned version of BMW’s 4.4L gasoline V-8 delivering 523 hp.

BMW has not divulged official performance figures, but Häcker suggests the M8 will significantly undercut the M850i xDrive’s claimed 0-62 mph (100 km/h) time of 3.7 seconds. Combined cycle fuel consumption is put at 22.0 mpg (10.7 L/100 km).

In a move mirroring that of the latest M5 and M850i xDrive, the M8 receives a standard 8-speed torque converter-equipped gearbox as well as fully variable xDrive 4-wheel-drive system and electronically controlled M-differential at the rear.

Similarly, the suspension is a development of the double-wishbone and multi-link system used by the M5. However, the M8 has a shorter wheelbase and wider tracks than its sedan sibling.  Added stiffening measures within the body structure make it more rigid than the M850i.

Häcker confirms the new 2-door receives its own specific suspension tuning, with tauter springs and firmer dampers than the M850i. It also gets revised bushings and roll bars.

“We’ve focused a lot on body control. It corners very flat and with very little movement. You sit a lot lower than in the M5, so it feels quite a bit different to drive,” he says.

Häcker also confirms the new M8’s center of gravity is 1 in. (24 mm) lower than that of the latest M5 and notes it boasts a 50:50 front-to-rear distribution of weight, in part through the adoption of a lithium-ion battery weighing significantly less than the lead-acid battery used in standard 8-Series models.