It's god advice. A mate bought an XKR to tour down to Italy and back, did just short of 6k miles, sold it for 500 sheets less than he paid when he got back. Winning, if you've got the 20k to drop in the first place
I've just rented an X3 for two weeks in Denmark, £835
If you do rent from the UK, I rented on and off for a few years with Enterprise and they were cheap and decent service in my experience. Watch out for excess waivers though, they don't push them aggressively but they are fiercely priced (e.g. £1k excess) to scare you into them. They did me a Diesel Estate Passat, it was a superb mile cruncher and super relaxing to drive, if a little bit of a boner killer.