Surge in New Models
A key factor driving auto sales will be the surge in new vehicles introduced in the U.S. A total of 43 new models will roll into showrooms in 2013, an increase of nearly 50 percent compared to 2012.
In addition, there will be 60 redesigned vehicles rolling into showrooms in 2013, also an increase over last year. The slew of fresh models will fuel increased interest by car and truck buyers looking for new models to replace aging vehicles.
"There's still plenty of pent-up demand for new cars in the U.S.," said Pratt. "The average age of cars being driven is still over 10 years and a lot of the people driving those cars will be looking to trade-in for something new."
16 Million Sales Possible?
The Polk estimate of auto sales hitting 15.3 million in 2013 is one of many forecasts calling for sales in the mid 15 million range. Is there a chance auto sales could surge to 16 for all of this year? Pratt says it's possible, though unlikely.
(Read More: Cheaper Midsize Cars Rated Safer Than Luxury Models)
"If the economy grows much faster than expected, it might happen," said Pratt. "More realistically, we won't see 16 million until 2014 or 2015.
Polk estimates new vehicle registrations will hit 15.8 million in 2014, and 16 million in 2015.
—By CNBC's Phil LeBeau; Follow him on Twitter
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