IRVINE, Calif. — Kelly Blue Book reports that new-car sales will total 16.9 million vehicles in 2015, up 2.5% from 2014 totals. KBB is also predicting that it will be the slowest year of growth for new-car sales since 2009, a year in which sales declined 21.2%

KBB offer other prediction as well. It said it expects incentive spending to rise to the highest levels since 2004 — averaging nearly $3,000 per unit. The vehicle information site said it also expects the average transaction price to rise this year, which should keep the ratio of incentive spending to average transaction prices at prerecession levels.

Reporting on 2014 trends, the site noted shifts in customer vehicle preference due to cheaper gas prices. The industry saw increased sales in crossovers and SUVs as a result, with sales of small luxury crossover vehicles and SUVs growing 18.6%. Sales in the mid-size segment increased by 12.3%.

Cheaper gas prices also affected other segments, with non-luxury car sales remaining essentially flat last year, up only 0.8%. Hybrid sales fell 11.5% compared with 2013, while full-size car sales dropped 9.8%. Overall, cars made up 46.1% of sales in 2014, the lowest percentage since 2005.

“Consumers shifted toward crossovers and SUVs in 2014 as gas prices fell to the lowest levels in more than five years,” said Alec Gutierrez, senior analyst at Kelly Blue Book. “If gas prices continue to stay at these levels, there will be growing pressure from manufacturers to revisit CAFE standards.”

Also in 2014, the average transaction price was $32,804, as more consumers opted for vehicles with more options.

Daimler posted the largest increase in its average transaction price, which increased by 4.9%. Mitsubishi reported the largest decrease in transaction price, which fell 4.1%.