DETROIT ( TheStreet) -- Who would have ever thought that Cadillac would lead the U.S. auto industry's sales revival? Not long ago, Cadillacs were "geezer cars," said independent auto analyst John Wolkonowicz. "You saw them at retirement homes, churches and old people's restaurants." In 2011, the average age of a Cadillac buyer was 57, compared to an industry average car buyer of 51, according to Polk. Only the Lincoln buyer, averaging 60 years of age, was older, Polk said. On Tuesday, GM ( GM) said Cadillac sales rose 38% for the first five months of 2013, the brand's largest sales increase since 1976, making the 110-year-old brand the fastest growing major automotive brand in the U.S. "Think about that," Kurt McNeil, vice president of sales operations, said Monday on GM's sales conference call. "We're talking about the days of disco, when Cadillac was strictly a U.S. brand back then, not one that's directly challenging the German luxury brands and gearing up to triple its sales in China over the next couple of years." Overall light-vehicle sales rose 8% in May, continuing a long recovery, with total 2013 sales expected to reach about 15.5 million, the highest since 16.1 million in 2007. The sales revival has been led by pickup trucks, light-utility vehicles and small cars, although Cadillac is showing the largest percentage gains off a relatively low base. "Older people are still the core of Cadillac buyers," said Edmunds.com analyst Jessica Caldwell. "You can't change the buyer profile overnight. But if you continue to bring out cars that appeal to a wider variety of people, it can happen." Cadillac's revival is being led by the ATS compact luxury sedan, the 2013 North American car of the year as selected by a panel of automotive journalists. ATS sold 3,249 units in May and 15,724 units in the first five months of 2013. GM said 70% of ATS sales are by first-time Cadillac buyers. The SRX mid-size luxury crossover is the brand leader, selling 3,744 units in May and 20,078 units in the first five months. The XTS luxury sedan, introduced last summer, had its best retail sales in May and sold 2,429 units. And the Escalade full-size SUV sold 1,928 units, its best May since 2008.