Notice that some coupons have a note to agents that say "At checkout - In AWD, enter ******* - In Coupon enter *******"
Be careful as this could raise the rate if they enter a new AWD.

The $25 off coupons don't have AWD codes.
The $25 off a three day rental coupon seems great as there is no restriction against using it on Premium cars that are "C" and above.
Coupon for $5 per day up to $25 good for any class of car even subcompacts.

Coupons "may not be used in conjunction with any other coupon, promotion or offer" so I doubt this means AWD code discounts but who knows.