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.
Neat. When I went to Pikes Peak a couple years ago, there were a few camouflaged Jeep Grand Wagoneers. Not surprised to see the mountain road as a common testing ground.