Michael R N Dolbear wrote:

Greek road vehicle number plates are Latin alphabet (except the Greek army
uses Greek).

No, they're the intersection of the Latin and Greek alphabets. So:
PHB 1234
could be read as pee-aitch-bee or rho-eta-veta depending on which alphabet
you use, but the plate is unique in either system. There are no letters
used which aren't in both alphabets.

The army and some older municipal vehicles aren't constrained by this rule
and use other parts of the letter space.

Theo