2004 Volkswagen Jetta Wagon 4dr Wgn TDI Manual exterior front left

2004 Volkswagen Jetta Wagon 4dr Wgn TDI Manual exterior front left

The price of gasoline may be falling now that the Fourth of July holiday is behind us, but that doesn't mean that car buyers have given up on fuel economy.

According to Carmax, which operates 100 used-car superstores and says it's the country's largest used-car seller, last month's searches for used diesel vehicles were up 7 percent over May and a substantial 12 percent over March. Hybrid-vehicle searches rose to a lesser degree, up 4 percent over May and 9 percent since March.

And interest in fuel efficiency continues to grow overall, with visits to the fuel economy section of the Carmax website up a whopping 17 percent in June over the month before.

Which vehicles were Carmax visitors searching for? Popular diesels included two trucks--the very large Ford F-350 and Dodge Ram 3500--and the always popular Volkswagen Jetta TDI.

With growing publicity about new clean diesel models from Volkswagen, Audi, and others, we expect interest in diesels to continue growing. That said, we still expect Volkswagen to be the big winner with its upcoming 2010 Volkswagen Golf TDI.

As for hybrid searches, the Toyota Prius was in the top models, of course, as well as the Honda Civic Hybrid and the luxury crossover Lexus RX400h.

2004 Toyota Prius 5dr HB (GS) exterior rear right

2004 Toyota Prius 5dr HB (GS) exterior rear right

[Business Wire via CNNmoney]