so a ferrari f12 is allowed?
Nah, there were a few more rules.
You couldnt drive anything with more cylinders than 6 (it may have >= 8, but there are no 7 cylinder cars I know of so that's largely theoretical).
None of the restrictions applied for diesels (i.e. v12 twin turbo diesel like Audi q7) and there was nothing about electric cars (Tesla roadster and p85d were fine)
The new rules are far better though, there was a limited amount of cars which should have been banned but weren't but for the most part they were all expensive. There's also a lot of potentially faster cars and even some old exotics (308) allowed under the new scheme.
The ironic thing is that I'm pretty sure the old rules were brought in to stop p platers driving the late 80s/90s v8 falcodores and turbo JDM imports - but now a lot of those exact cars which a p plater might have feasibly afforded back then are legal.