Nissan Motor Co. filed a trademark infringement suit against Audi Tuesday, claiming the German carmaker poached the letter Q for its new Q7 and Q5 sport utility vehicles.

Nissan has used Q as the first letter identifying some of its premium Infiniti vehicles -- such as the Q45 and QX4 -- since 1989. It has registered the names and a slogan "the new Q" with the U.S. Patent and Trademark Office.

"Audi's immediate and threatened use of the Q5 and Q7 trademarks is likely to cause confusion, deception ... among consumers, thereby infringing Nissan's Q Marks," Nissan said in the suit filed with a U.S. District Court in Michigan.

Nissan asked the court to bar Audi from using Q7, Q5 or any other names that infringe on its 'Q Marks'. It is seeking damages from Audi, a subsidiary of Volkswagen AG, and reimbursement for legal costs. Nissan officials would not specify the damages sought.

Audi has not seen the lawsuit, spokesman Doug Clark said. "It is our policy not to comment on pending litigation," he said. Audi plans to build a Q7 SUV and sell it in the United States next year. It may offer a smaller Q5 SUV later. Audi, based in Ingolstadt, Germany, has also begun a "Q7 Globe" advertising campaign on its website.

"We've used Q since 1989," said Bill Garlin, spokesman for Nissan's Infiniti division. "No other company to date has used Q to identify a vehicle."

In its suit, Nissan said its Q45 sedan was widely known as "the Q", and it adopted the slogan "the new Q" in 1993 to describe redesigned versions of the Q45. It also uses G, I, M and F as the first letters in its vehicle names.

Most Audi vehicle names begin with the letter A, such as the A6 and A8 sedans, although Audi identifies performance versions with an R and has a TT coupe in its lineup.

Audi is an older brand renowned for its technology, but Infiniti outsells Audi in the competitive U.S. car market.

Last year, Infiniti sold 130,987 vehicles in the United States, compared with 77,917 for Audi. But the German carmaker has ambitious plans to increase U.S. sales.