Now we wonder how often this stuff happens in the industry.
It's common practice for automakers to purchase cars from other companies when developing a new model. After all, everyone is really building the same thing but with slight proprietary tweaks. When Honda was developing the new NSX it bought a Porsche 911 GT3 to study its steering. Usually these purchases go unnoticed, but Porsche got wise to the truth. Nick Robinson, the vehicle dynamics project lead for the NSX, told Automotive News that Porsche left a little message for his team.
According to Robinson, Porsche didn't initially know that the 911 GT3 had been purchased as a research vehicle. However, when the car came in for a recall to fix the engine connecting rods the secret came out. The Porsche techs looked into the black box data and discovered that the 911 had hit 205 mph. When the car was returned a Porsche employee quizzed the person picking it up, likely not Robinson (he didn't mention who picked it up), asking them where they hit 205 mph and on what track. When the team popped the hood they found a message written on the engine cover. "Good luck Honda from Porsche. See you on the other side."
The automotive industry is fiercely competitive so it's nice to see that Porsche had a sense of humor about one of its cars being used as a competitor's tester. Robinson told Automotive News that the team also bought a McLaren 12C for research, and despite taking the supercar in a few times for maintenance no one from the English company ever realized what the car was being used for.