You'll know, but often too late. Older passats have the R36 label on the back left. Some new cars (superby, etc.) have two antennas. Fin and rod. Which no one puts on the car anymore. The superbys use Ramer radars, which can be identified by our anti-radar radar. He wants to drive adequately, according to the Highway Police, there is almost no risk of retribution within 150 km / h. In any case, they will stop you in a lawful way, with an inscription behind the window.