AWD = Avis Worldwide Discount. An Avis AWD number is a discount code that helps you save on your rental car and may come with other benefits. Browse the linked table below for some current offers.
https://www.avis.com/en/offers/us-offers/coupon-codes

Quote:

MileagePlus Cardmembers can earn United TravelBank cash on qualifying Avis and Budget car rentals.

- $25 in United® TravelBank cash, up to $50 annually, for your 1st and 2nd car rental paid for with your United℠ Explorer Card or United℠ Business Card
- $40 in United® TravelBank cash, up to $80 annually, for your 1st and 2nd car rental paid for with your United Quest℠ Card
- $50 in United® TravelBank cash, up to $100 annually, for your 1st and 2nd car rental paid for with your United Club℠ Card or United Club℠ Business Card

https://cars.united.com/

The Avis savings of up to 35% off and the Budget savings of up to 30% off applies to the pay later base rate, which includes time and mileage charges only. Use AWD # A791500 and BCD # B204900 to receive this discount. . . .

https://cars.united.com/en-us/mileag...and-conditions