BMW’s sustainable supercar

Published: May 3, 2014 10:35 a.m. ET




BMW of North America

Frank Lloyd Wright called the practice of architecture “sublimated mathematics,” and I invite you to think of car design the same way. Beneath the wind-raked, time-traveling skin of the BMW i8 luxury hybrid lurk a lot of large and unesthetic numbers. The biggest is the daily parts per million of carbon in the Earth’s atmosphere, now over 400 and going nowhere but up. European car makers are under social, political and regulatory pressure to reduce greenhouse emissions.

Which brings us to another number: 2 billion euros ($2.77 billion). That is a conservative estimate of how much BMW BMW, +1.07%  has spent to create, from scratch, the “i” brand devoted to building sustainable electric and hybrid-electric vehicles. The program has its own carbon-neutral supply chain, starting with the hydroelectrically powered facility in Moses Lake, Wash., that makes the carbon-fiber thread from which lightweight vehicles are built. The i cars are assembled at a Zaha Hadid-designed facility in Leipzig, Germany. They will be available in the U.S. in September. (I’ll have a proper review of the i8 this summer.)

BMW's i8 Tech will influence future cars

With its i8, BMW goes on a radical program of weight saving to make modern cars fast and efficient. Dan Neil says this approach will change all the cars we’ll drive in the near future. Photo: BMW.

And the pace of spending has been impetuous. At one point last year it was rumored the program development was consuming the entirety of BMW Group’s R&D budget. The car you see here, this heroic portent of what’s next, was a mere 38 months in development.

“There were long nights,” said Carsten Breitfeld, director of the i8 project. “Some nights when we went to bed not sure how to go forward.”

These exertions reflect the stubbornness of the next number. Well, actually, it is a function, and one that has bedeviled car makers since Gottlieb Daimler: energy density, or the amount of energy stored, divided by mass. Barring some as-yet-undiscovered propulsion pixie dust, any car that can operate in electric mode needs batteries. Even the best lithium ion batteries are heavy and lack the energy density of our old friend, gasoline. If you want a low-emission or no-emission plug-in with no decline in performance relative to gas, you have to make the car lighter. Radically lighter.

After much consideration, BMW’s engineering management concluded the only way to do that was to reinvent the automobile. And that is where the 2 billion euros went.

The first i product was the i3, introduced last fall. It is a quick, big-on-the-inside urban EV with a range of about 81 miles, costing about $41,350, before federal and local credits. The i3 brought to market the program’s signature LifeDrive technology: All the car’s moving parts, the machinery, is packed into a lightweight aluminum Drive chassis, like a roller-skate truck. The body of the car, the passenger safety cell, is spun out of a light, strong carbon-fiber reinforced plastic (CFRP). And the two modules, Life and Drive, are essentially glued together, meshing on the assembly line like two sides of a zipper. The resulting car is 2,860 pounds.

While there are historical precedents, cars have never been made like this before. For a fairly apples-to-apples comparison, the steel-bodied Mercedes-Benz B-class Electric Drive, which had its first media drive in Silicon Valley this week, weighs 3,858 pounds. The i3 is 998 pounds lighter, fully 25% less.

So what, big deal? Bear in mind that reducing mass in automobiles, making them lighter, does a lot of fantastic things for you, engineering-wise. It puts you on a positive spiral, because lighter cars accelerate faster, turn harder, stop shorter, with less wear on tires, brakes and cooling systems, which means those parts can themselves be lighter.

Crucially, they need less energy to move, and that is convenient in the case of electric cars because less energy is just what the batteries offer. The i8 takes the LifeDrive technology and sexualizes it, in a dead-cool, modernist luxury GT complete with corner-gripping all-wheel drive and wing doors.


The i8 isn’t a small car. Its profile suggests a midengine Italian berlinetta, but the surface is buckled with Starship Trooper panels of immaculate futurism. Among the car’s alluring details is the flying buttress: As it travels rearward, the roofline detaches from the tapering canopy, creating an aero tunnel between it and the curvaceous rear fender. The i8 is a car half-drafted in negative space, with the dorsal flourish of black plastic and glass stabbed through the middle of the canopy. The contrasting surface details are metaphoric, meant to suggesting a peeling away of layers, a skin shed, the emergence of something new.

Like the i3, the i8’s powertrain parts (an internal combustion engine and electric-traction motor) are integrated into two aluminum Life modules. Ahead of the front aluminum bulkhead is a powerful electric traction motor, about the size and shape of a pumpkin. This hybrid synchronous e-motor generates a stout 184 pound-feet of torque, channeled through a two-speed gearbox. Buried behind the rear bulkhead is a tiny 1.5-liter, turbocharged gas engine producing 228 hp and 236 pound-feet of torque, putting power to the rear wheels through a six-speed automatic transmission. In between, nestled in the aluminum deck, is the liquid-cooled 7.1 kwh battery pack.

And like the i3, the i8’s passenger cell comprises a complex, hollow sculpture of carbon-fiber reinforced plastic. These are by no means the first cars to use CFRP. It is a common enough material in low-volume sports cars such as Lamborghinis and McLarens; race car “tubs” are also typically made from carbon fiber. But CFRP has never before been used in mass production, due to the cost, complication and cycle time of producing carbon-composite parts. The conventional method involved hand laying the carbon fabric in piece molds, investing them with resin, sealing them in vacuum bags and autoclaving them for hours. In contrast, the i8’s Life cell emerges out of the process in a matter of minutes.

BMW of North America

Every millimeter of the i8 has been scoured of excess grams. Example: The i8 is the first productioncar to use chemically hardened thin glass, a material previously used only on consumer electronics such as cellphones. The sinuous, flowing skin is made from easily replaceable polycarbonate panels, roughly half the weight of steel (the doors and hood are skinned in aluminum).

The key metric is the car’s weight: 3,455 pounds, about the same as a Chevrolet Corvette even with the lithium battery pack. Meanwhile, the i8, being BMW’s technology flagship, comes loaded: 8.8-inch display with 3-D navigation graphics; an array of connectivity functions; Harman/Kardon audio system; optional laser headlamps (not DOT approved, as yet) and heads up display.

Which brings us to another amazing number: 3. That is the number of cylinders in the i8’s fiercely turbocharged 1.5-liter gas engine, situated amidships. A decade ago it would have been unthinkable for a company to launch a flagship sports car with 3 cylinders, when all the world knew V8s and V12s had the power.

But with the help of the car’s carbon-intensive diet, the bottled lightning from the electric motor up front, the two transmissions and lots of extremely clever software, three cylinders turns out to be plenty. The i8 accelerates from naught to 60 mph in 4.2 seconds—as quick as a Porsche 911—gets to the quarter-mile traps in about 12.2 seconds, and doesn’t trim its electric sails until it hits 155 mph. The system net horsepower is 357 hp—modest by modern standards—but the coordinated torque of the turbocharged gas engine and e-motor (totaling 420 pound-feet) accelerates the car like a thrown javelin. The throttle is responsive and properly, effortlessly muscular, as all GTs must be.

In the end, it is about that first number, daily ppm carbon. According to EU standards, the i8 produces 49 grams per kilometer, and sips fuel like a hummingbird, getting the equivalent of 135 miles a gallon. BMW says that isn’t representative of real-world efficiency in the U.S. Instead, it says it is more like 50-60 mpg, about the same as a garden-variety Toyota Prius. Like all plug-ins, the more you plug the i8 in, the more efficient it is. Dust-to-dust, cradle-to-grave, the i8’s carbon footprint is, BMW estimates, roughly a third of a conventional automobile’s.

If all of that seems a little cloudy and technical to you, just think of tennis rackets. Remember when carbon-fiber replaced aluminum? Remember how great that was, how that changed the game? BMW has just done the same.

Maybe you’ll never buy an i8. They are, after all, $135,700 to start, right in the range of a Mercedes SL63 AMG. But the i program’s technology will resonate in car design for decades to come. Numbers don’t lie.

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