Sign into the airline's website using your frequent-flyer number and go to the mileage redemption page.
Click on the car-rental option, which is often listed under the hotels link. Enter your pick-up and drop-off cities, dates, and times in the request form. If you have a certain car in mind, you may also filter your selection at this point or opt to explore all of the available car categories.
Review the list of car options. The list will only display cars from rental companies that partner with your chosen airline and accept its mileage points. Each selection will indicate the number of points needed for the length of your rental, as well as a thumbnail photograph with the make, model and features.
Make your car selection and you will be guided to a summary page for review. Read through the rental agreement and make note of any taxes and fees that have to be paid in addition to the points. Fill out the payment screens. If you don't have enough mileage points, some car rental companies will allow you to pay with a combination of miles and money. Airlines will also sell additional miles for a fee.
