Overnight GM showed off a heavily camouflaged photo of its next-generation Chevrolet Volt, which we'll again know as the Holden Volt.
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The side-on shot (above), with Volt chief engineer Andrew Farah parked in front it, reveals nothing that our earlier spy photos haven't already shown. What was more interesting was what the company said about the car's camouflage.

Every car maker worth their salt has a large proving ground filled with all types of road surfaces, corners, obstacles and high speed loops. Despite that, automakers still need to test new cars out in the open under real world conditions.

That means having development cars and prototype out in public view before they've been unveiled, released, announced or even approved. That's where camouflage comes into play.

At GM it's actually the engineering department that's in charge of designing and applying a car's camo.

That's because while the disguise is designed to keep as much of the styling under wraps as possible, it can't interfere with the elements that the engineers want to test.

Adding excess weight makes it makes it hard for the development team to get a fix on the car's real world ride, handling and steering characteristics, while camouflage that blocks airflow and alters the aerodynamic properties can throw all manner of other tests out of whack.

According to the company, black and white patters are often the best because they create shadows and help to hide design features. Swirls are also in vogue at the moment, because, unlike earlier grid designs, they're easy for engineers or designers to remove and reapply whenever changes underneath need to be made.

Layered levels of disguise can also help, so long as they don't interrupt airflow. More obtrusive camouflage, especially the stuff that's used in the earlier stages of testing, can be made from almost anything, including plastics, vinyl or foam. But apparently, bubble wrap is a cheap, lightweight and easily affixed 3D material that's good at confusing the minds and the eyes of onlookers.

According to Lionel Perkins, GM's camouflage engineer, "Each car is unique. We are like a dress maker, and the car is our model. No two models are the same. We need to make the right dress that fits the body we are dealing with."