Well, I'm flying with BA to LAX and at ba.com/avis they're giving me better rates than any AWD at avis.com. The only problems are that I then have to pre-pay and can't enter any coupon. I called the Avis customer service and they said they can't add a coupon to reservations made via ba.com. Maybe it's possible at the desk, but I wouldn't want to be greeted with

[rap]
This coupon is no can do,
you'll have to make do
with this Malibu
[/rap]

I'll save $50 by booking a full size rather than a premium, but if I can't be sure that the coupon will be accepted at the desk, I think I'll pay the extra money to be guaranteed a premium car. I'm only Preferred, so can't expect an upgrade without a coupon.