BMW’s first plug-in hybrid vehicle will focus not just in saving the earth, but also on satisfying its driver’s need for speed. Like the Chevrolet Volt, the BMW i8 concept combines a traditional gasoline engine with an electric drivetrain. According to BMW, the i8 can be as fuel-efficient as the best hybrid cars, while still delivering sports car-like performance.
An electric motor drives the front wheels, while a traditional gasoline engine drives the rears. The i8 can thus act as a front-, rear-, or all-wheel-drive car depending on which power sources are running. An “energy tunnel” containing the battery and drivetrain electronics runs down the middle of the vehicle, connecting the two axles.
The electric motor and engine peak at a combined 349 hp and 406 lb-ft of torque. That means the 0-to-62-mph sprint requires just 4.6 seconds. Top speed is electronically restricted to 155 mph. BMW says overall economy in European testing will be 2.7 liters per 100 kilometers, or 87 mpg. In real-world driving, the company expects the i8 to return mileage of 33 to 47 mpg. As gloating company executives note, no other production car can return the same combination of performance and economy.
The front-mounted electric motor is the same unit used in the i3 electric-car concept, but it is slightly modified to offer 128 hp and 184 lb-ft of torque. Because the i8 also has a gasoline engine, the electric motor’s battery pack is significantly smaller than that in the i3. The i8 has an all-electric driving range of about 20 miles and can be fully charged in just under two hours. The electric motor can also recharge the battery, acting as a “through the road” hybrid system that can bolster the engine’s output.
At the rear axle, a turbocharged 1.5-liter three-cylinder engine produces 220 hp and 221 lb-ft of torque. BMW would only tell us that the engine is mated to an “automatic” transmission with “enough” speeds. It may be a traditional automatic or perhaps a dual-clutch unit. However, BMW doesn’t think the transmission in the i8 is very important to discuss as the electric motor provides plenty of torque regardless of the gasoline engine’s operating speed or gear.
Sports Car of the Future
The i8’s styling is meant to reflect its sports-car intentions, with low-slung coupe design and doors that flip open butterfly-style. The i8’s styling was heavily inspired by BMW’s earlier EfficientDynamics concept. The doors and roof are totally transparent, a styling choice which looks fantastic and futuristic but is unlikely to reach production. The swooping roofline and aggressive front fascia seem much more likely to show up in your local BMW dealership.
The i8 wears BMW’s trademark kidney grilles at the front, as well as LED headlights and a black plastic V-shaped element on the hood. The nose looks remarkably like that of the old BMW M1 or 8 Series, with the headlights and grille taking on a rectangular, pouty look. At the rear, silver plastic panels meet to form the “Stream Flow” line on the C-pillar, while a small diffuser cleans up air from beneath the car.
At 182.4 inches long and 77.0 inches wide, the i8 casts the same size shadow as a BMW M3 coupe. Yet at 50.4 inches tall, the i8 is only two inches taller than a Ferrari 458 Italia. The aluminum wheels measure 19 inches in diameter and will probably wear tires between 225 and 250 millimeters wide. Narrow wheels were chosen because they produce less drag and rolling resistance, and don’t intrude as far into the cabin as the wider wheels used on normal sports cars.
Like the i3 electric car, the i8 is built using BMW’s new modular LifeDrive chassis architecture. In the case of the i8, two Drive modules — housing the gasoline engine and electric motor, respectively — sandwich the Life passenger compartment. The Life section is decorated in a mix of clear glass and black plastics, while the Drive sections are painted silver.
The Life compartment is made from carbon-fiber reinforced plastic (CFRP), which is said to be as strong as steel but 50 percent lighter. The Drive units are built from aluminum, which BMW says is about 30 percent lighter than steel. On top of those units, traditional plastic is used for the actual body panels. The i8 weighs just 3256 pounds, and because the two drive units are at opposite ends of the vehicle, the i8 has a perfect 50:50 weight balance.
The even weight distribution and multi-link suspension design should conspire to make the i8 handle as well as BMW claims. The front suspension even has special geometry designed to reduce torque steer from the electric motor. The front brake calipers will likely be made from aluminum to cut weight, as regenerative braking and low weight reduce the need for enormous friction brakes. Even though its tires will be relatively narrow for a sports car, BMW engineers assure us the i8 will have “enough” grip for sporty cornering and braking.
To help keep aerodynamic drag as low as possible, the bottom of the i8 is completely flat. Special cut-outs called AirCurtains in the front fascia direct air around the front wheels to reduce turbulence, while the rear decklid and blue rear diffuser are designed to further improve aerodynamic efficiency. Air flows through the Stream Flow channel and under the “floating” taillights, which apparently helps aerodynamics. BMW wouldn’t talk about a specific drag coefficient for the i8, but said the number would be “record breaking.”
BMW elected a driver-focused look for the i8’s interior, with a big shift lever sprouting from the center console and flat-screen gauges directly in front of the driver. Occupants sit low in the car, with the hump created by the battery pack running down the middle of the cabin. The i8 is officially a 2+2, so although it has seating for four, the rear seats are extremely cramped. The trunk holds just 5.3 cubic feet of cargo, the same as a Mazda MX-5 roadster.
The center console is also home to the BMW’s iDrive controller, parking-brake button, and engine start/stop button. Two 8.8-inch touch-screen displays present information on everything from the radio and navigation systems, to battery charge and electric range. The interior is finished in a mix of Porcelain White plastics, Stream Blue accent trim, and Mocha Brown leather.
There are two special driving modes available in the i8: ECO PRO adjusts the accelerator sensitivity and climate control to improve efficiency, turning the gauges and illuminate blue in the process. Sport mode, as the name suggests, is meant for enthusiastic driving and brings a large, orange-lit digital speedometer to the forefront of the displays.
To keep energy efficiency as high as possible, the i8’s navigation system will pre-determine which powertrains to use for different parts of the journey. It might run the gasoline engine on the highway, for instance, then switch to electric power for the final few miles of a trip.
The Future Might Arrive in 2013
The numbers sound like the perfect convergence of performance and eco-mindedness: 0 to 62 mph in 4.6 seconds, 155 mph, and 87 mpg. That assumes that BMW actually builds the car as seen here. The i8 is still a concept car at this point, and its styling will undoubtedly change before it goes on sale in 2013. We also have yet to hear a definite price tag. BMW says the car will return a profit, so given how much technology and materials research went into the i8, it’s a fair bet the car will be expensive. We had previously heard the i8 could cost as much as [euro]120,000 (about $171,000).
The BMW i8 will debut publicly at the Frankfurt Motor Show in September, and should go on sale by the end of 2013.