National Car Rental launched its annual One Two Free Emerald Club promotion on Aug. 16 for the 10th consecutive year.

The promotion offers registered Emerald Club members one free rental day for every two qualifying rentals, with no limit on free days earned. The promotion runs from Aug. 20 through Jan. 31, 2013, and the rental days can be redeemed from Sept. 10 to June 15, 2013. Free rental days can be redeemed online, over the phone or at the counter.

Customers can join National’s Emerald Club at www.emeraldclubpromos.com/12Free/2012 to participate in the “One Two Free” promotion. There are no fees to join and new members can enjoy its benefits of faster service at airports and free upgrades in National’s “Emerald Aisle.”

Participating members can also earn a free rental day for referring a friend or colleague to the Emerald Club by sharing the “One Two Free” registration link via email, Facebook or Twitter.

“From the very beginning, the ‘One Two Free’ promotion was designed to offer special rewards to our loyal Emerald Club members as a way to say ‘thank you’ for choosing the National Car Rental brand,” said National Assistant VP Rob Connors. “Ten years later, we are pleased to continue offering this rewards program to new and current members who rely on the Emerald Club for speed and convenience during their business and leisure travel.”