Alan Helfman has no doubts about the strength of the economy. He owns Ford and Chrysler dealerships in the affluent Houston suburb of River Oaks, Texas, and is selling vans, Jeeps and Ford Explorers like "gangbusters."

"We’re hot as fire down here," he drawls. "It’s not the best it’s ever been, but it’s pretty dang close."

Defying predictions, American consumers continue to open their wallets — and fuel economic growth. Economists say businesses let their inventories dwindle early this year and then were surprised by consumers’ resilience. But now, as they rush to restock their shelves, economic growth could pick up in …