ATLANTA — AutoTrader.com's July Trend Engine report indicated that shoppers continued to show interest in big trucks and SUVs while production shortages for new cars, coupled with continued short supply of quality used cars, pushed asking prices higher across new, used and Certified Pre-Owned (CPO) vehicles.

"The combination of consumers holding on to their cars longer, leasing drying up and the lack of new-car sales in 2009 and 2010 has caused a dearth of late-model quality used cars being available for sale in 2011," said Rick Wainschel, AutoTrader.com's vice president of automotive insights. "This short supply has put tremendous pressure on the used and CPO market, pushing prices higher. Additionally, production shortages in the new-car arena have had a similar effect."

Shoppers briefly turned their attention away from big trucks and SUVs earlier in the year when gas prices were nearing $4.00 per gallon, but with the steady decreases in June and leveling off in July, shoppers kept their sights on these vehicles, according to the company.

"Every time gas prices start increasing, there's a threshold at which consumers start focusing more on fuel efficiency than other considerations,” Wainschel said. “However, that threshold becomes a moving target with each major increase, as shoppers' tolerance for what they pay at the pump eventually goes up."

Trucks and SUVs continued to make big gains on the list of most-searched new vehicles in July, with seven full-size trucks and five SUVs (including crossovers) dominating the list. Nearly all of the full-size trucks on the list made month-over-month gains in popularity, with the Dodge Ram 2500 moving up seven spots to No. 16 in July, the Chevrolet Silverado 2500 moving up four spots to No. 14 and the new Ford F-150 and F-250 moving up two spots to No. 1 and No. 11, respectively. The new Chevrolet Silverado 1500 also moved up one spot to No. 5.

On the SUV side, the new Jeep Grand Cherokee moved up two spots to No. 19, while the new Ford Explorer moved up one spot to No. 10 spot. Additionally, the new Kia Sorento moved up seven spots to No. 20.

As was the case in June, compacts took another hit in popularity in July and generated less consumer interest on a month-over-month basis. The new Volkswagen Jetta dropped two spots in July to No. 12 and the new Ford Focus dropped six spots on the list. At No. 8, the new Chevrolet Cruze was the only compact to stay put on a month-over-month basis.

Similar trends were seen on the list of most-searched used vehicles, as many full-size trucks moved up in popularity month-over-month while luxury and smaller cars declined.

On the list of most-searched CPO vehicles, full-size trucks and SUVs remained relatively flat, with only a few standouts in the crossover category. The CPO Honda Pilot moved up three spots to No. 13, while the CPO Toyota Highlander dropped two spots to No. 16. The CPO Honda Odyssey was the only minivan to make list in July, moving up three spots to break into the top 20.

Year-over-year average asking prices for the majority of the most-searched new vehicles on the site continued to increase in July, with 14 out of 19 going up. Of those 14, nine vehicles have asking prices that are at least $1,000 higher than they were during the same time last year. 

For the most-searched used vehicles, prices increased on a year-over-year basis for 12 out of the top 20 vehicles. The biggest price increases were for smaller cars, including compacts and mid-size sedans. All four of the vehicles fitting into these two categories saw average asking price increases of over 10 percent.

While many used trucks and SUVs gained in popularity, average asking prices for these vehicles saw modest decreases on a year-over-year basis. The used Ford F-250 and used Dodge Ram 1500 both saw decreases over 3.5 percent, while the used Chevrolet Tahoe took the biggest hit in asking price, declining 10.6 percent.

Average CPO asking prices increased on 17 out of 20 vehicles, with 13 showing year-over-year price increases over $1,000. These increases signal a high demand for quality, late-model used vehicles, which have been facing supply issues across the board.