SAN FRANCISCO — Manheim’s chief economist, Tom Webb, delivered the company’s annual Used Car Market Report at the 2011 National Automobile Dealers Association (NADA) Convention and Expo. Webb announced gains in both new- and used-car sales in 2010 but noted that many of the key factors that drive the auto retail market and the economy in general, including employment rate and average household net worth, are not likely to approach pre-recession levels anytime soon.

“It’s an upbeat forecast,” Webb said. “Some of our projections are actually above the consensus.”

One example is 2011 new-vehicle sales, which Webb believes may eclipse the much-discussed 13 million-unit mark forecast by most sources. He noted that much of the credit for the 2010 “rebound” of the new-vehicle market — 11.6 million units sold, an 11 percent increase from 2009 — should go to fleet sales, which increased by 22 percent.

However, Webb expects only “marginal” improvement in that category this year. “We need employment growth,” he said, alluding to the modest gains to the employment rate that have characterized the current period of economic recovery.

Leasing also saw gains in 2010 after dramatic losses in prior years. New-vehicle lease originations surged to 1.7 million in 2010 after falling to 1.19 million in 2009. Such gains are not likely, however, to offset an inevitable dearth of off-lease units in 2011 and 2012.

Webb applauded dealers for demonstrating an increasing sophistication in inventory management in 2010, despite a still-shrinking supply of wholesale units.

“New-vehicle sales will not be as competitive vs. used,” Webb said, predicting that “less supply, stable demand and strong pricing” will continue to drive that market.