This article from wired.co.uk covers it very well.
I have copy pasted a portion here...
Simulation and modelling also allows GM to measure its new designs against those of competitors before a single weld is made or body panel is stamped. But in order to benchmark against the competition in the virtual realm, GM needs accurate engineering data on its vehicles-something competitors aren't exactly willing to give up themselves.
The beginning of the teardown process is a friendly pass. "First, we want to scan as much as we can without disassembling the vehicle," Pecar said. Next the exterior is scanned with a large blue-light scanner, and then red light scanning is used for details like the interior and seam tolerances. Finally, the position of components is recorded to help put all the pieces together again digitally as the teardown commences.
Things start getting unfriendly here. Each component of interest is scanned as the car is disassembled piece by piece. "You can look at a muffler and red-light scan it... it all goes back to the body position of the original model," Pecar said. Some individual pieces, like the muffler or a headlamp, may get cut open and scanned internally to build engineering models from.
The end result is a complete set of reverse-engineered computer models of the vehicles brought into the Teardown. In some cases, those models can be even more accurate than the ones used to design the vehicles in the first place. After all, they show the vehicles as-built.
Models are shared with GM's designers and engineers, who can use them to study the end product of competitors' design processes and learn from their successes and failures.
I have to say things appear to have moved along a notch since I was last in GM's benchmarking area (Mona Lisa... I have no idea why its called that) in the 1990s.
When I put forward my proposal for an educational venture, I looked at the competition. BPP own Phoenix University.
They have several physical campuses in Michigan.
They appear to be successful. The group also has a UK footprint.
Benchmarking a successful company, obviously makes more sense than failures. Particularly, if you are trying to attract investment!
Going back to the GM article, I do find the 3D printer and its uses enthralling.
GM obviously use scanners to reverse engineer. They then use that math data to design around/compare with their products and /or they 3D print it!
An educational institute could obviously do that too. Enabling students to design a part or parts and then send it to a 3D printer and physically produce it in a quick and cheap manner is a very real option.
People like to touch and feel. Designers do too. Virtual is great. HOWEVER! 3D printing brings the design alive. I think its a great addition to the design process.
Here is a video, from YOUTUBE, where the CEO of AUTODESK Carl Bass talks about design and 3D printing. Carl, obviously deals with blue chip companies, and small start ups, as well as individual consumers.