Welcome Aleksi,
Not sure what you mean about our car numbers, do you mean the registration plates or the VIN plates on UK market cars ?
Our car registration plate system is strange, everything from 2 letters/numbers up to the current system where the first two letters show the region or area where the car was first registered, the next two numbers show which time of the year, and the last three letters are random.
For instance AB 07 CDE would be Anglia (where I live) March 2007 till Aug 2007
We can also buy older numbers that may have a significance for us, like our names initials or car models etc.