BMW i8 Concept, foto and info

It’s been nearly two years since BMW’s Vision EfficientDynamics concept debuted at the 2009 Frankfurt show, and the car has now officially re-emerged one step closer to production as the BMW i8 concept.

As you can see, little has changed in the styling department. In fact, other than a new wheel design, the only other notable change we’ve spotted concerns the doors, which seem to have claimed some territory along their bottoms and thereby reduced the size of the blue body-side accent. Interestingly, the car didn’t show that change when BMW paraded it around for spy photographers this past March, but we like it.


Passenger Compartment + Powertrain = LifeDrive

As with the i3 city car concept that debuted at the same time (you can read about it in full here), the story of the i8 begins with its so-called LifeDrive architecture. BMW says that its experiences in creating the Mini E and 1-series-based BMW ActiveE showed that adapting cars engineered for internal-combustion power to electric propulsion results in a lot of excess weight and compromises in packaging.
As a result, both the i8 and i3 are built using two purpose-built modules: one to house passengers, dubbed “Life,” and one for propulsion and suspension components, called “Drive.” Combine them, and you have a car—and marketing-friendly “LifeDrive” branding.

While the i3 and i8 share the LifeDrive architectural philosophy, the cars differ in execution. That’s because the i3 is fully electric, while this i8 is a plug-in hybrid. The i8’s powertrain is split between its two axles, with an electric motor and direct-drive transmission at the front axle and a gas engine and transaxle at the rear.

Interestingly, the battery packs in the i3 and i8 use different lithium-ion chemistries, as well as unique shapes. The large, square pancake battery of the i3 is designed for longer distance travel—in other words, it has a lot of energy—and is located below the passenger compartment. In contrast, the i8’s lithium-ion cells protrude into the coupe’s Life space, where, as in the Chevrolet Volt, the liquid-cooled and -heated battery stack fills a hump that could be mistaken for a transmission tunnel. The i8’s elongated pack is designed to deliver shots of power in short spurts; the final spec is yet to be decided, but it should have a capacity of around 8 kWh.

Arranging the pack this way allowed BMW’s engineers to achieve yet another claim of perfect 50/50 weight distribution, thereby preserving peace in the city of Munich. As in the i3, the i8’s Drive components are largely crafted of aluminum, while the Life module uses a carbon-fiber skeleton wrapped in thermoplastic exterior panels.

So much lightweight material allows the i8 to use a smaller, lighter battery than would be needed if the car were made of heavier steel. This frees up room in the cabin, and, more important, keeps the curb weight around a svelte 3300 pounds. The rigidity imparted by the carbon fiber also allows for long, dramatic doors that ease access to the two small rear seats.

While most other hybrids are based on existing front-drive vehicles, BMW had the luxury of starting from scratch. As with all 50/50-balanced cars, the majority of braking forces occur at the front axle. So, in the effort to recoup as much energy from regenerative braking, it makes sense for BMW to fit the electric half of the powertrain up front. The i8 uses a modified version of the i3's electric motor, with a peak output of 129 hp and 184 lb-ft of torque. It’s fed juice, of course, by those lithium-ions, and takes about two hours to charge from a 240-volt trough. Battery topped off, the i8 will return 20 miles of all-electric driving.

Three’s Company: 220-Horse Three-Cylinder

The original Vision EfficientDynamics concept used a three-cylinder turbo-diesel engine, but the i8 makes use of a gas-fired turbo three-cylinder that may turn out to be the best part of the powertrain puzzle. It is a version of BMW’s new modular engine on which we first reported in April. It displaces just 1.5 liters, features direct injection, a turbocharger, variable camshaft timing, and variable intake-cam lift. It makes an astonishing 220 hp and 221 lb-ft of torque. Altogether, the hybrid powertrain makes 349 hp and 406 lb-ft of torque. That puts this car in elite company within BMW. Think M company.

The i8 weighs slightly less than a 1-series M, and makes more power and torque. BMW says the i8 is governed to 155 mph and it will accelerate from 0 to 60 mph in less than five seconds; think more like low fours with a quarter-mile time of less than 13 seconds. But where the 1M gets, at best, 26 mpg on the highway, BMW says the ocho should return real-world, combined fuel economy near 40 mpg. One area of concern for twisty-road seekers is its tires. They are narrow, of the low-rolling-resistance variety and will thus suffer in limit grip. We hope there’s an option box for summer tires. Learn More..

Source : http://www.caranddriver.com