Many businesses and consumers need to replace older trucks and cars. The average age of a U.S. vehicle is 11.2 years. Plus, automakers have rolled out dozens of exciting new models in the past year, drawing buyers into showrooms."Relatively lower gas prices coupled with small business demand improving for trucks resulted in a strong showing for small and large pickups in April," said Jesse Toprak, senior analyst for the TrueCar.com auto pricing site. One category that's soaring is small crossover SUVs. Sales are expected to rise 22.5 percent, according to Kelley Blue Book. Fuel-efficient models such as the Ford Escape, Honda CR-V and Mazda CX-5 are driving sales up, Gutierrez said. Of the major automakers, Nissan Motor Co. is expected to post the largest sales gain. Several analysts expect an increase of more than 20 percent. Gutierrez said the midsize Altima is driving sales. Nissan normally boosts sales in March to finish out its fiscal year, then sees a drop in April, he said. Last year the company had a big April decline, Gutierrez said. GM, Ford, Chrysler and Volkswagen all are expected to post double-digit gains for the month. Kelley Blue Book expects auto prices to fall slightly in April compared with a year ago, to an average of $31,326. Although the year is turning out to be strong for auto sales, Gutierrez said not to expect the double-digit growth rates of the past two years. He expects U.S. auto sales to end the year around 15.3 million cars and trucks, up 5.5 percent from last year's 14.5 million.