Porsche
They had GA manufacturer plates on the rear with EU plates on the front. The drivers wouldn't say what they were doing with them, just that it was secret. All the logos were removed. No significant differences between them on the exterior, but they had different exhaust configurations.
Hey everyone, a few pictures of cars always help to get a community going. This is my 2014 Cayman S, on Glendora Mountain Rd north of Los Angeles. Post yours!
 Took my son, his buddies, and my girlfriend to Pikes Peak. I love my 997, but these cars made me feel inadequate.
www.pca.org
May be old news by now but glad to see this thing go to someone who cares about Porsches and drove it.
I don't have a Porsche, but I'm eyeing a Cayman GTS and hoping to get one soon. Figured I'd create this community so that others can join and post. :)