Members of Air France/KLM's Flying Blue loyalty programme can earn double miles when renting a car with Sixt until November 30.
For every rental, members will receive 600 miles, or 2,000 miles for every rental of seven days or more, double the standard 300 and 1,000 miles respectively.
The offer is available on every rental worldwide and is valid for bookings made via the Flying Blue website until October 30 for car pick-up until November 30.
Members will also receive a 15 per cent discount when renting in Barbados, Costa Rica, Curaçao, the Dominican Republic, Guadeloupe, Martinique, Panama, Saint Martin and Sint Maarten.
Members must present their Flying Blue membership card when collecting their vehicle from Sixt.