These camouflaged cars aren't hunting or on a battlefield, but may be hiding a big secret

Long before a new car model hits showroom floors, it often takes its maiden voyage in a very incognito — and strangely scientific — way.

In order to study the real-world performance of a new vehicle, automakers need to log thousands of miles on public roads for years leading up to the car's debut. When the new model finally hits showrooms, car companies want the design to look fresh, so preserving the auto's true looks until near the time of sale is a top priority.

Enter car camouflage, which may conjure up images of soldiers on a faraway battlefield, but actually serves a unique purpose: Providing cover for prototype cars as they roll through the streets on test drives.

Early in development, deception comes easy. Developing a car's powertrain — key components that fire up the vehicle and make it move — starts with "mules": prototypes that use the bodywork of existing cars. For example, Rolls-Royce uses a lifted body shell of its Phantom sedan to develop the underpinnings of its upcoming Cullinan SUV.

"Early on, they disguise it in a way that you can't even tell the shape of the car," Brenda Priddy, a famed "spy photographer" who has made a living selling shots of camouflage-laden prototypes to automotive publications, told CNBC recently.

Changing bodywork, however, affects weight and handling characteristics. To sort out ride and handling, companies usually switch to the body structure of the upcoming car. Then, bulky, foam padding is added to cover up important details and disguise the shape of the car.

"These are typically for vehicles with very telling proportions like an MX-5 [Miata]," Ken Saward, a senior design manager at Mazda North America told CNBC. "They may put a station wagon back on it so you can't possibly render what the vehicle underneath looks like."

Eventually, however, car companies have to test the real-world fuel economy, performance and durability of new designs. The padding, which disturbs aerodynamics and blocks cooling, has to go. With all of the bulky trickery and testing mules gone, they begin to play games with your eyes.

That's where the special version of camouflage comes in. Most of these patterns are derived from World War I-era "dazzle" camouflage, which was designed to be difficult for an eye to focus on. Such vessels were devised to make it difficult for enemies focusing on a ship, or to determine its speed and distance.

Because the human brain is so pattern-oriented, it has a difficult time discerning details of a shape when a pattern is layered on top.

"When you do camouflage pattern for hunting, the goal is that animals can't see you because all of the different lines break up the pattern of a person," Edward Rupp, owner of Graphik Concepts, told CNBC. "On cars, it's the same thing."

Graphik Concepts, based in Farmington Hills, Michigan, has worked with automakers like General Motors and Nissan for more than 20 years supplying camouflage and other wraps to the automotive juggernauts. Over that time, they've cloaked dozens of prototypes.

The patterns they've developed help to hide shadows, making it difficult to determine a surface's shape or style. With key details obscured, it's often near impossible to recognize a vehicle if it's draped in camo.

"The goal is that you don't know what the car looks like until GM releases it," Rupp said. "When you see it camouflaged, you can't tell what the body contours are. Especially from a distance."

Intrepid photographer Priddy, however, argued that camouflage doesn't fool her. In fact, she says the patterned wraps make her job easier. Automakers claim that camouflage disguises the prototype and interferes with the autofocus on cameras, but she saw it differently.

"I don't find that to be the case at all ... I've never had problems focusing on them," Priddy said. "For a professional…the wraps just aren't that successful."

Yet for carmakers, it isn't all about stopping trained eyes from working out details. It's about preserving mystery for the big reveal.

"You need something to keep people anxious and waiting for the new car to come out. It's like how you don't see the bride until she walks down the aisle. You don't take pictures of her while she's getting ready for the wedding," Saward told CNBC.

For his vehicles, it's the same story.

"It looks really ugly covered in wraps and vinyl, so when it comes out and you see it in a beautiful Soul Red with nice wheels it will still look like a new design," Saward added.