Incentives are taking their toll on U.S. retailers.
Stores that focus on the used-car business have struggled as automakers wrap new vehicles in pretty incentive packages.
Large vehicle inventories and prolonged economic uncertainty further hurt the retailers.
Only AutoNation posted a gain in the first quarter, up 1.5 percent.
No retailers showed an increase over a year ago -- AutoNation fared best with an 8.8 percent decline.
"Retailers show signs that they have the intention and funds to continue the trend of (mergers and acquisitions)," says Jay Singer, a PricewaterhouseCoopers director.
"Same-store sales have been offset by continued growth. The challenge is in maintaining existing business."
CarMax, spun off by Circuit City in October 2002, led the three-year period with an increase of 339.5 percent.
CarMax plans to open new outlets during its current fiscal year in Las Vegas; Chicago; Orlando, Fla.; Kansas City, Mo.; Birmingham, Ala.; Memphis, Tenn.; and Louisville, Ky.
Lithia Motors turned in the worst first quarter, down 21.6 percent, and worst three-year performance, down 19.3 percent.
Sonic Automotive posted the biggest decline among one-year performances, down 51.0 percent.