If a recession is under way, this economic recovery will have been the least beneficial one ever for the new-car dealers. The best inflation-adjusted year-over-year increase in their revenue during the recovery was 6.9 percent, far below the peaks of other recoveries. There is, of course, no mystery now as to what the problems are for car dealers. They are pinched by the slumping real estate market because people can take less money out of home equity to buy cars. And soaring gasoline prices have made driving much more expensive and new-car payments more burdensome. In July, sales at gasoline stations accounted for 10 percent of all retail sales, the highest figure in decades. Dealers are hurting. The rest of us may soon share their pain.