The cost of a weekly economy car rental (automatic transmission, A/C, unlimited mileage) in Andalucía for a UK resident: £157. The cost of the same rental for a US resident: $650.
Something to be said about the inter-EU travel.
On the other hand, business-class-only MaxJet tickets cost almost 50% more (at the current exchange rates) if paid through a UK “gateway”, and our upcoming Swiss ski trip would cost 60% more if we were to book it through a non-US agency.
Go figure!