United Airlines Mileage Plus. Earning miles with Car Rental

Car rental	You'll earn	Current offers
Alamo	500 Miles per rental
Avis	50 Miles per day	Rent for 1-2 days and receive 50 bonus miles. Rent for 3 days and receive 250 bonus miles or Rent for 4 days or more and receive 750 bonus miles
Budget Car and Truck Rental	50 Miles per day
Dollar Rent a Car	50 Miles per day	Mileage Plus members will earn triple on rentals of a Compact car or larger vehicle for 2 days or longer at participating locations worldwide.
Hertz Car Rental	50 Miles per day	Get a Free Day and earn Double Miles when renting an economy through full size car for one or more days at a participating location in Mexico through December 31, 2011.
National Car Rental	50 Miles per day
Sixt	500 Miles per rental
Thrifty Car Rental	50 Miles per day