So who gets the 4% of turnover GDPR fine here? Or is it under the law enforcement exemption?
I'd be surprised though if it is really run by the council or just contracted out to some outsourcer. In which case they should be fined.
It might take a few years, but you can use this dataset in the future to understand who owned the vehicle at this time and reconstruct their movements.
Using collected information it's possible a computer can remember every journey you've ever taken; this car with this reg plate was here at this time at this place, and they did not have a valid tax/insurance at this time, or it could be useful during investigations
It seems analogous to an IP address in that sense, and the courts have ruled that IP addresses are personal information.