I was following this Audi (latest A4 I guess? It seems recent and I do not recognize the taillights), but it is not for the Audi that I took the pic...



Yes, a Ford Crown Victoria here in Brussels
Not easy to take a good picture with a cellphone at 120 km/h, luckily it was driving rather slow so I could pass the Audi and take a pic of the Ford.
I guess both were together: both had diplomatic plates (Belgian plate for the Ford, Luxembourgian plate for the Audi).

A little later I saw a GMC Savana, also with diplomatic plates. With original US taillights (red blinking light as turn indicator).