Rally car's number plate/licence plate

[TWRC]

Hungary also has sport numberplates, with "SP 00-00" format. You can only use a car with that plate on a test or event (officially of course). I think they introduced this to try and counterbalance the flood of Slovakian sport numberplates (at one time, about 80% of cars competing here used Slovakian plates, mainly with Komarno and Kosice registrations). What was strange is that I saw a couple of these numberplates also used in the UK, and Wevers Sport has one Fabia R5 with SP numberplate too.

[electroliquid]

Some Lithuanian driver using cars with Estonian sports car registration and number plates, due smaller taxes, I heard. So maybe that could be a case there too?

[Mirek]

Yes, it was somehow tax or insurance cost related. For some time Slovak number plates were quite common in CZ as well.