I’m no expert but from what you’ve said, I take it that you’ve booked the accommodation separately?
If that’s the case then I’d say you haven’t booked a package holiday by definition. Yes, you’ve bundled flight and car hire together (and possibly accommodation too) but even booking these at the same time through the same company (or rather their partner companies) wouldn’t qualify as a package deal.
Just my reading of the situation, I may well be and hope I am, wrong.