Automakers' gross sales statistics notwithstanding, it's not always easy to understand how car sales are stacking up in the real world. Nation's largest automotive retailer AutoNation (AN 0.54%) knows, and on Tuesday, it announced its latest sales figures for new-car sales for the month of May.

According to the Fort Lauderdale, Fla.-based retailer, it moved 26,372 pieces of metal in May 2013, 11% more than it sold in May 2012. Some of the growth came from new store openings, but same-store sales were still up 8% year over year.

Domestic American brands experienced the strongest growth, up 14% in comparison to May 2012, with 8,287 units sold.

Imports outsold domestics at 13,181 units, but their growth was slower, up only 7% year over year.

Meanwhile, consumers proved happy to open their pocketbooks to pay for luxury brands. AutoNation only sold 4,904 of those, but the growth was a strong 17%.