As above, but it all seems variable. There is a current BA/Avis deal (until 15 Apr) for additional avios, but when I search with avisba.com (or carrier-ba.com), I only get Budget options. If I use avis.co.uk, I can see that they have cars available at the same place at about the same rates. We used Budget last time in the US as the rental place was opposite the hotel and it was fine, albeit less convenient than avis preferred, and with no additional driver.