Calgary-HQ’d agency Critical Mass has won AutoTrader.com‘s digital account. As the newly-picked interactive AOR for Atlanta, Georgia-HQ’d AutoTrader.com, the Omnicom-owned digital agency will help promote new cars and trucks in addition to pre-owned vehicles, including the interactive component of the site’s latest national campaign.

(The Canadian version of the site launched its campaign along with New Car Magazine in April, with John St. handling creative, Cossette Media the broadcast buys, and OMD the online buying. AutoTrader.ca is not affiliated with AutoTrader.com in the U.S.)

The Critical Mass team will develop and execute digital strategies for the brand, including B2C and B2B efforts using e-mail, house ads, microsites, mobile, online media, rich media, and search. AutoTrader.com aggregates more than three million vehicle listings and attracts over 13 million qualified buyers each month.

Critical Mass also has offices in Toronto, Chicago, New York, Las Vegas, Atlanta, Austin, Geneva, and London.