BMW i focuses on efficiency

  • 18-Apr-2011 05:08 EDT
BMW3-11 i cars.jpg

BMW has only released hazy images of its new electrotechnology-led i brand models—but there is nothing hazy about a program that should see the i3 in production in 2013.

BMW is a company that thrives on advancing technology, and it is strengthening that philosophy with the development of its new "i" sub-brand. The first model—with carbon fiber (CFRP) bodyshell and slated for production in 2013—will presage a range of highly distinctive, dedicated designs aimed at taking the company firmly into the potentially burgeoning electric-vehicle market.

Dr. Klaus Draeger, BMW’s Board Member responsible for Development, told AEI that weight saving via use of CFRP for the body-in-white, low-rolling resistance tires on large diameter but relatively narrow tires, and aerodynamic efficiency are each key to achieving required range and performance in a vehicle that promises to be cleverly packaged and aesthetically attractive—although full details and images have yet to be released.

The extensive use of CFRP for the body, and aluminum for the chassis, would see a weight saving of about 300 kg (660 lb) compared to a conventional steel application. The application for a medium-volume vehicle, of what is still classed as an exotic material, will be made possible both by reduced costs and because the weight saving it would engender would offset the use of smaller, less expensive batteries with no range loss penalty while retaining the sort of driving dynamics expected of a BMW.

The first BMW i vehicle will be the four-seat i3 (previously referred to by BMW when discussing future direction as the Megacity Vehicle), a pure electric car for urban areas. This will be followed by the 2+2 coupe i8 based on BMW’s 2009 Vision EfficientDynamics concept. It will be a high-performance plug-in hybrid.

Although the two cars will be different in terms of role, cost, and performance, they will share a lightweight architecture, which sees an aluminum chassis housing the powertrain attached to the CFRP passenger cell.

“We call this a split into ‘Life’ (cabin) and ‘Drive’ (axles, high-voltage storage unit, battery, electric motor, ECU) modules,” explained Draeger. “We are very confident that the models will meet all criteria for safety—not only those necessary to conform to regulations but also consumer tests.”

He said it was too early to discuss aerodynamics and a Cd figure in detail for the LifeDrive cars, but certainly the i3 is expected to have thinner wheels/tires than the current norm to achieve the double benefits of improved aerodynamics and lower rolling resistance. Draeger said he did not believe that wide wheels and tires were necessarily essential for driving pleasure in such an application.

Batteries will be lithium-ion, he stated. “But we see progress coming in battery technology as more and more companies, driven by need, move into the area of 'electrotechnology.' In the short term (this decade), there is no alternative to lithium-ion, but research into different material combinations that have better performance potential in terms of energy density is going ahead; one example is lithium-sulfur. That new technology may phase in from 2018-22.”

Draeger said the most difficult challenge the i brand is bringing to engineers is the need to balance the manifold needs of customers together with entry into a new technology, while giving assurance to buyers of vehicle reliability and longevity without having limited functional applications. “It is going to be a regular car,” he said.

While the i cars’ construction will bring new design opportunities, they also bring challenges (including aerodynamics) while still being good to look at, said BMW Design Chief Adrian van Hooydonk. “We are very aware that we need to optimize aerodynamics because it immediately pays off with range.”

This even applies to the essentially urban i3 solution because of the need to ensure that it can be used as a “regular car,” which must include motorway driving. “The basic layout of the vehicle is in the vertical; this is different to the normal, which is in slices in the horizontal," said Hooydonk. "So that brings totally new propositions—and those opportunities apply to both vehicles.”

He said it was not possible yet to talk in detail about the design of the new models. “But for the i3, it has led to a very space efficient vehicle because the passenger cabin sits on top of the drivetrain and does not impinge on the interior, which is very roomy within the dimensions of a pretty compact vehicle," he explained.

“It is the first time a company is using industrialized carbon fiber in this way (rather than just for very low-volume vehicles or in small quantities). The material can be shaped every which way, so there were virtually no limitations for us in the form or shape of the vehicle. We are quite happy with that.”

Other than some injection-molded body panels, it also meant the designers were dealing with just one material. “When you see the finished vehicle, it will look as if the future has arrived; our new cars will be fun to look at and to drive,” said the enthusiastic Hooydonk.

That signature will “not necessarily” continue through other elements of BMW’s model ranges. The i is a sub-brand and the message is basically efficiency, so the design signature will look clean, aerodynamically efficient, and light.

But two cars do not make a brand, said Hooydonk. “There is room for more, and it’s all hands on deck for our engineering and design teams to make it happen. As always, the big challenge is a race against time. We want to deliver the i3 to market in 2013; this would be OK for normal technology, but for such a radical approach as the i cars it is very fast.”

Ian Robertson, BMW Main Board Member for Sales and Marketing, emphasized the use of CFRP instead of steel as a direct trade-off to battery cost. The increasing use of carbon fiber should at least start to achieve economies of scale and lower costs for a material which, in the automotive industry, has so far been reserved for super-premium high-performance cars. The aerospace industry, though, has made extensive use of it—the new Boeing 787 being a particular example.

The material will be supplied to BMW by the U.S. company SGL Automotive Carbon Fibers (in which it has a significant holding), manufactured in Washington State using hydroelectric power and shipped to BMW’s Leipzig factory to be formed into the vehicle’s structure.

Robertson adds: “Sustainability is here to stay. The price of oil will continue to rise, and the regulatory framework across the world continue to tighten.”

Some €400 million are being invested in the Leipzig plant. Development and production synergies will be achieved through both i3 and i8 vehicles (and doubtless further i variations) using the same component sets for the electric motors, power electronics, and batteries.

Robertson described the i3 and i8 as representing “bookends” for a new range. All models will see an increasing commitment by the company to onboard communications, allowing car-enabled mobility services such as use of existing parking spaces, intelligent navigation systems, intermodal route planning, and premium car sharing.

BMW i Ventures, a venture capital company, is to expand the range of services offered by BMW i by taking stakes in what BMW describes as “highly innovative service providers.”

New York-based My City Way is the first company in which BMW i Ventures has taken a stake. As a mobile app, it provides users in more than 40 U.S. cities with information on public transportation, parking availability, and local entertainment. Another 40 cities are scheduled to be part of a global rollout.

Automakers and the auto industry are plainly moving into a totally different era, with fresh criteria and applications for design and engineering, electronics, infotainment, and marketing, all of which will need to achieve a convincing level of integration.

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