I'm driving between road courses at BMW's test facility in the South of France. The preproduction i8 is nearly silent, a slight whine from the front-mounted electric drivetrain makes it into the cabin. The engineers' attempts at willing the car into good behavior are nearly as loud and far more perceptible. Although the i8 represents a significant technological leap for BMW, I can't get my first experience with an e36 M3 out of my head. The e30, BMW's first M3, was a raucous car. The lightweight special was little more than a racecar with power windows. The e36 was different. It was bigger, faster and more advanced and showed that BMW really had its heart in its heritage and its head in the future. While modern M3s might be a little too brainy, the i8 reminds me that BMW still has a heart.
BMW's new i-Division is the opposite bookend to the storied M. Both brands exist not only to offer cars too extreme to be main-stream BMW products, but also to develop new materials, processes and technology that will eventually trickle toward the center of the shelf. Without a doubt, some of the weight-saving improvements i-Division has found need to find a direct and very quick path from offices "i" to "M".
The i8 is split into two sections, LifeDrive and the Life module. The LifeDrive contains the rear gasoline powertrain and the front electric powertrain, both mounted to aluminum sub-frames. The mid-mounted battery pack is contained in another aluminum structure that also functions to connect the two power sub-frames. The Life module is a carbon fiber cell containing the cockpit and provides the main structure of the vehicle.
BMW not only builds the composite structure, but has gone as far as to control the process of making its own carbon fibers. It has partnered with composites firm SGL to build a new facility in Washington State to take polyacrilonitrile fibers imported from Japan and convert -- by burning them -- into carbon fibers. The spools of carbon fiber are sent to Germany, where they are woven into fabric. The fabric is then cut to shape, placed into molds and turned into structural CFRP (carbon fiber reinforced plastic) panels using an RTM (resin transfer molding) process. The panels are then stuck together using a high-tech adhesive to create the Life module.
Close examination of the life module reveals a structure not unlike a conventional unibody made of stamped steel panels welded together. Since composite panels need to distribute forces over a greater area to optimize fiber strength, greater overlap is required than with steel or aluminum. The front and rear sub-frames are both bolted and glued to the Life module. The bolts serve two main purposes. First is positioning during construction and also to avoid peel separation. The adhesive used to hold the two pieces together acts like Velcro. Over the entire surface area it's strong, but it can be pulled apart if attacked at a small corner and worked apart a little at a time.
While the uni-body, including the pillars and roof, are all carbon fiber, the body panels, with the exception of the front and rear bumpers, are aluminum. The door panels are built with a carbon fiber structure under a bonded aluminum skin. Although the diagonal-wing hinged doors are larger than average, they are half the weight of traditional car doors. That seems to be a major theme in the 3300 lb 2+2. While most car companies pat themselves on the back for taking 12% of the mass out of a component, BMW engineers list part after part that's tipping the scale to the tune of 50-60% less than normal. That explains how a hybrid is 900 lb lighter than the current M6.
Starting at the rear of the i8 is the main power unit. A transverse,228 hp, 1.5 liter, turbocharged, inline-3 cylinder. The engine is mated to a traditional 6-speed automatic. This will ring a bell when we start talking about the next generation of Mini Cooper. A small electric motor is mounted to the ancillary side of the engine. It's used as a starter motor, generator to charge the batteries and to supplement engine power when the turbo isn't producing boost. At the front, a 129 hp electric motor is mated to a 2-speed transmission. The lower gear is only used in full electric mode, while the taller gear is used during mixed power operation. An engineer happened to mention the electric motor has a 40 hp reserve that could be used later. The current output of the electric motor was chosen to optimize the grip available at the front tires.
The car can be driven in one of three modes. In E-mode, the car runs entirely on the 6.0 kWh lithium-ion battery and electric motor. BMW claims a range of 22 miles with a top speed of 75 mph. In comfort mode, both power-trains are used and the battery is allowed to drop to 20% capacity before the gas engine is used for recharging. In comfort mode, BMW is claiming 95 mpg. This is on the European test-cycle and includes the mileage gained from the plug-in hybrid system. In sport mode, both powertrains are constantly used. The generator is used to keep the battery at 80% capacity as much as possible to maximize performance.
The steering and suspension are both tuned for sporty driving and BMW claims a 0-60 mph time of less than 4.5 seconds.
The Other Stuff
The i8's interior is nothing shocking if you've been in a BMW lately. The seating position is low and my 6-foot-2 self had plenty of head room. The seats are supportive and the steering wheel isn't too thick like several recent offerings from M-Division..
The instrument cluster is fully digital and entirely too busy. Lights flash and streak across the display all the time. So much information is being displayed that I ignored the whole thing after just a few minutes. I'd show you what I mean, but BMW wouldn't let us take any pictures of the interior. The rear seats are unusable for anyone but children although the big doors make access easier than in most coupes.
The suspension components for the i8 are sourced from other BMW models. The weight-saving efforts are again obvious as unnecessary material has been drilled or machined out. While the suspension components are the same as other cars, the i8 benefits from a lower center of gravity and lower polar moment of inertia. The battery pack is mounted as low as possible and centralized which is an ideal start, add to that the front and rear power units are almost entirely between the axles. The layout of the car is nearly perfect.
While the exterior of the car I drove was still camouflaged, the work that has gone into aerodynamics is obvious. Engineers have spent countless hours on BMW's rolling-road wind tunnel to optimize flow. Small intakes in the front bumper pull air in from the high-pressure area next to the main inlet, direct it around a channel in the bumper and blow it out at the edge of the wheel well in front of the tire.
Apparently the front wheel wells can account for as much as 25 percent of a car's drag, and those "air curtains," as BMW calls them, have made a drastic reduction on that number. Air brought in through the front intake is redirected over the top of the car through the hood extractor, and flow over the top of the rear fender is pulled behind the car with the buttresses running down the C-pillar. In front of the rear wheel wells, more intakes are visible at the back of the rocker panels that feed cooling air to the engine, while two more intakes in the car's flat undercarriage provide more air. One intake cools the rear exhaust silencer. All of this adds up to a slippery 0.26 coefficient of drag.