BMW Vision EfficientDynamics
Gov. Arnold Schwarzenegger of California sat behind the wheel of the BMW Vision EfficientDynamics concept car this week at the Los Angeles auto show. But just before the futuristic car’s trip out West, it made a stop at BMW’s offices in New Jersey to inform and inspire the staff.
I stopped by to look at the car, which BMW engineers argue may create a quiet revolution in body shapes. They explained that one reason for the plug-in diesel hybrid vehicle’s loopy, layered forms is the role that BMW’s new rolling road wind tunnel played in its design.
The tunnel is changing ideas about aerodynamics. Previous wind tunnels only tested the car with its wheels fixed. But rolling wheels have many aero effects, in interaction with wheel wells and the pavement. Aerodynamically, rotating wheels are a mess, which is why some concept vehicles cover them with fender skirts or spats.
Using the new wind tunnel, BMW engineers and designers have developed features that are likely to show up soon on production models. One is called the air curtain, which channels air smoothly through the car’s front end into the front wheel wells and over the wheels, eliminating drag there.
The Vision EfficientDynamics’s outer shell is all about aerodynamics. It hovers over the primary, inner structure in layers. “We are able to optimize the airflow,” said Adrian van Hooydonk, the BMW Group design boss.
The sides of the car appear to have been sliced and folded down, as if for an autopsy. The sheets of carbon-fiber body are white, their edges accented with blue. (Blue and white are the BMW and the Bavarian colors.) The A-pillar directs air in a thin sheet over the greenhouse; the rear end seems to be wearing a cape or hoodie.
The separated parts recall so-called naked motorcycles, where parts stand separate from an internal skeleton.
Expect more innovations from the BMW aerodynamicists: A smaller version of the rolling road wind tunnel, using half-scale models, lets engineers test the effects of wind at oblique angles and when one car passes another.