BMW has made the i8 hybrid supercar into a really, really cool i8 Roadster with a new design, more power, and a better battery. Launched at the LA Auto Show, the i8 Roadster and its new and improved i8 coupe companion get a couple of new color options and some copper upholstery.
The BMW i8 began selling in 2014 as a 2+2 coupe made of carbon fiber and pure hybrid awesomeness. With sleek, concept car looks and a forward-thinking powertrain design, the i8 proved to be a sensation. A tiny, turbocharged aluminum rattlebox of an engine powered the i8's rear wheels and an electric motor churned the front for all-wheel drive excellence.
Now that formula has been enhanced with a refurbished design, some battery and motor tweaks, and the introduction of a two-seat topless i8 Roadster. Both new models of the BMW i8 shown in LA are due to enter showrooms as 2019 model year entrants.
Before we look at the new Roadster, let's jump into the guts of this newly-updated i8. The key ingredient is a new lithium-ion battery pack developed specifically for the i8 thanks to BMW's practice with the array of plug-ins the company has produced since the i8's introduction. Located in the car's underbody, underneath the passenger cabin, the battery provides the i8 with a low center of gravity. It's cell capacity is increased from 20 Ah to 34 Ah, boosting energy capacity from 7.1 kWh to 11.6, giving it a net energy capacity of 9.4 kWh (usable).
This battery boosting has meant that more power can be directed to the electric motor, bumping it by 12 horsepower to 141 horses in all (105 kW) and 184 pound-feet (249 Nm) of torque. This means 0-60 mph (0-92 k/h) times of 4.2 seconds for the Coupe and 4.4 seconds for the Roadster, BMW says. Top speed is electronically limited to 155 mph (249 km/h). Those lighter of foot can cruise up to around 18 miles in all-electric mode.
The engine remains the same award-winning three-cylinder, turbocharged 1.5-liter, producing 228 horsepower (170 kW) and 236 lb-ft (320 Nm) of torque. A six-speed automatic transmission runs the engine's power to the rear wheels while the electric motor has a two-speed automatic gearbox turning the front wheels. Improved efficiency measures give the BMW i8 an expected MPGe of 70 and BMW believes that the Roadster will retain that same fuel efficiency.
The new i8 Roadster model is basically a chop-top version of the i8 Coupe with the rear seats removed in order to make way for the folding rooftop and its mechanism. That soft, fabric top, BMW says, opens and closes in 16 seconds and can do so while driving at up to 31 mph (50 km/h).
Interestingly enough, it stows in a perpendicular position behind the passengers. This allows some extra storage space behind the driver and passenger, a space almost equal to the actual trunk's 4.7 cubic foot (133 liters) offering at 3.5 cubic feet (99 liters). That nearly doubles the amount of storage available in the Roadster versus the i8 Coupe.
Components on the new i8 Roadster's convertible roof mechanism are made out of aluminum using a new 3D printing process. This allows for geometric parts that cannot be cast for the optimum strength and size to be used, balancing weight with rigidity requirements.
The 2019 BMW i8 Coupe and i8 Roadster will enter showrooms globally, starting in the second quarter of 2018. New color schemes being offered include E-Copper metallic and Donington Grey metallic, both with Frozen Grey metallic accents.
The i8 Roadster will have exclusive 20-inch BMW i light-alloy wheels in radial-spoke style, lowering wheel weight by about 2.2 pounds versus the other wheels offered on the i8. Badging on the rear (B) pillars will indicate Coupe or Roadster according to the model chosen.
The interior of the 2019 BMW i8 sees design changes for infotainment and driver information screens. The Giga and Halo interior trim options remain available and a new Tera World Copper has been added. BMW is also offering a new charging system through its 360 Electric program that can charge the i8 Coupe or Roadster to full in less than three hours.
Source: BMW
One thing I think would be nice on a roadster with quick acceleration is an electronic limited slip differential for the rear wheels. With synergy style gear reductions between the front motor and the front wheels, a small motor clutched to drive either planetary gear could enable torque vectoring without braking while keeping most of the front driving power in a single large motor.