Just received this in the email:

As an Omni Select Guest member, you can enjoy a free one-car group upgrade on qualifying rentals of three days or more. This offer is valid on intermediate through full size four-door rentals at participating Avis airport locations in the U.S. and Canada until December 31, 2007. Simply provide coupon # UUHA012 when you make your advance reservation.

Also, remember to use your Avis Worldwide Discount (AWD) number G009000 to receive up to 20% off your next rental. Just another way we try harder to make your trip better.