The App shows Preferred Plus for me as well. Some parts of the website still say I'm Avis First though.

I received a weekend coupon this week (expiring 9/30 as others have noted), and in the body of the email, it has the following text that wasn't in the one I got in February:

"Coming soon—you'll have the opportunity to start earning rewards with the enhanced Avis Preferred program. All newly issued Weekend Reward coupons will have an expiration date of 9/30/15.

Stay tuned for more information about your Avis First membership and the new Avis Preferred program."

Personally, I love (and will miss) the weekend coupons -- I use them for those cases when I need to rent somewhere that has obscene weekend rates (PHX sometimes, for example).