Unique to the i3 and i8 is BMW’s â€œLifeDriveâ€ architecture. In a typical family car, the monocoque construction means that the body and chassis are one structure, with all important components – engine, suspension, seats, dashboard – bolted to it. BMW has decided to separate the mechanical structures of the car from the occupant space, and created two horizontally separated modules. The Life Module is naturally, the passenger space. Made of CFRP (Carbon Fiber Reinforced Plastic) the lightweight cabin is conceptually similar to the driver cell of a Formula 1 race car.
The Drive Module handles the duties of crash resistance and mounting the driving hardware, while packaging the heaviest components and battery in such a way to maximize occupant space and safety. Such an approach was previewed nearly a decade ago by GM’s Hywire â€œskateboardâ€ concept. BMW however has beaten GM’s advanced concept to market.
While the i3 concept was shown in an electric-only configuration, both it and the i8’s Drive Module can be configured to accept a range-extender gasoline engine. In the i8 sportscar, the i3’s rear-mounted electric motor was moved to the front of the chassis, while a high performance 3 cylinder engine is fitted over the rear axle. In both the i3 and i8 the electric motor produces 125kw/170hp of energy, and a stout 185lbs/ft of torque from a standstill. The range-extender engine in the i8 produces an additional 164 kW/220 hp and 221 lb-ft bringing the total power output to 390hp and 406lbs/ft – figures equivalent to the 2011 BMW 650i luxury coupe. Yet unlike the highly consumptive 650’s 23mpg top highway figure, the i8 promises an outstanding 94mpge on the European combined cycle. With a projected curb weight 1000lbs less than the 650’s porky 4300lbs performance should be stunning as well.
What BMW is promising with its radical LifeDrive architecture is an advanced concept of how occupants can be better packaged within a variety of bodystyles. The i3’s compact hatchback body is roomy, and airy and provides storage space both in the nose and behind the rear passengers. The i8 on the other hand eschews practical space for a laid-back coupe layout. Yet unlike the massive luxury coupes it currently makes, there is plenty of space for 4 occupants to enjoy the blistering performance.
The CRFP body structures of both cars is innovative as it brings a material only found in supercars to the wider public. Carbon fiber has been around since the 1980s, when it was debuted on race cars. While lighter than aluminum, the complexity of working with the material has limited its application to high-cost vehicles. In the i family of cars, BMW touts a 50% reduction of weight over steel while managing to have finally developed a mass-production facility in the United States (In Moses Lake, Washington) for volume production.
The carbon fiber sheets that BMW has developed in conjunction with SGL Automotive Carbon Fibers can be worked like a fabric into shapes unimaginable in steel or aluminum. As a result, both the i3 and i8’s bodies feature radical shapes to help control the flow of air around the car, improving efficiency while simultaneously creating an aesthetic previously only enjoyed by owners of exotic machinery.
The i3 and i8 portend a complete rethink of the car as we know it. While current electric and hybrid efforts from manufacturers package new-think drivetrains into old school sheetmetal, BMW has decided to circumvent this cautious evolution to create cars it is convinced buyers will flock to. Radical materials, and construction are only one patch in the greater Project i quilt. All the cars and their components are slated to be built in facilities using 100% renewable energy. The cars themselves are seen as a part of a greater mobility project where BMW is rethinking the role of how cars are used in cities, and how we own cars.
That the electric motor module in the i3 is the size of 2 cases of beer underscores the change afoot at the company with the name of Bavarian Motor Works. If the i3 and i8 deliver on their promises of high performance with little ecological impact then automakers will be on notice to radically redefine their plug-in offerings in their shadow.