<font face="Verdana, Arial, Helvetica, sans-serif" size="2">Originally posted by Rut Dog:
in order to get the 500 Avis, you must give your HH number to both Avis and the Hotel. This is not clear from the T&C, but something I learned here (from Eugene).</font>
Actually, here is how it works.
You need to choose at the Avis counter whether you want airline miles or HH points (with Avis, it's "either or" deal, while with the rest of HH car rental partners you can get both). If you rent from Avis not in conjunction with a HH stay, you'll get 250 HH points per rental, no matter how long. If your Avis rental is in conjunction with a HH stay, you'll get extra 250 HH bonus points (to the total of 500 HH points). As long as your HH stay is eligible for points and is in your name, you do not have to mention Avis at the hotel.
When renting from other HH car rental partners (e.g., Thrifty), you can request airline miles at the Thrifty counter, then show your keys or rental agreement at check-in at Hilton and get 250 bonus HH points.