If you’ve been wondering where BMW’s ‘Project i’ field study program is headed, the wait is over. BMW has now announced its intention to produce a radically different urban electric car in 2013, a departure from the more conventional MINI E and 1-Series ActiveE battery electrics this automaker has focused on in recent years. BMW’s four-passenger premium city car is dubbed the ‘Megacity Vehicle.’
Megacity is a term used to describe the largest population centers on earth. In these busy, crowded environments, many traditional vehicles are too large or simply too inefficient. The Megacity Vehicle is a purpose-built urban transport that’s designed and engineered from the pavement up for its intended mission. A pure EV, the Megacity Vehicle is actually the latest in a long history of electric drive vehicles from BMW. Forty years ago, BMW produced a small fleet of bright orange electric 1602 sedans to serve as marathon support cars for the 1972 Munich Olympic Games. Electric drive development continued over the next four decades with several notable concepts, then shifted into high gear with the current Project i program that launched in 2007.
The Megacity vehicle will break new ground on several fronts, not the least of which is body structure. While most lightweight cars tend to use unibody construction, the futuristic BMW will be body-on-frame. But this body-on-frame design is very unique, featuring an all-aluminum frame to carry the suspension, battery, and electric motor that will be mated to a carbon fiber body structure.
BMW’s design places the large lithium-ion battery pack mid-ship between the frame rails to maintain a low center of gravity. This location also protects the pack of 96 4-volt cells, which are wired in series and encased in an aluminum housing. Battery cells are from German supplier SB LiMotive. The rear frame section is a large cast aluminum structure that serves as a mount for the Megacity Vehicle’s 134 hp (100-kW) brushless electric traction motor. The rear-drive layout was in part chosen to maintain BMW’s legendary driving dynamics.
At half the weight of a steel body and 30 percent lighter than aluminum, the carbon fiber body is truly space-age construction. BMW has developed proprietary manufacturing techniques to make all the pieces come together and will produce the carbon fiber material through a joint venture with SGL Automotive Carbon Fibers at a new facility in Moses Lake, Washington. Besides being lighter, carbon fiber is also corrosion resistant and five times stronger than steel. We witnessed the results of initial crash tests of the body and frame structure while in Germany, and came away thinking it’s no wonder they make Formula 1 race cars out of carbon fiber. Simply, impact absorption and damping are impressive.
We will bring you more details on BMW’s ‘premium, clever, and clean’ Megacity Vehicle as this program progresses.
