TUCSON, Ariz. — From cooling systems to alternative fuel, the University of Arizona's Earth Day celebration featured up-and-coming and existing eco-friendly cars.

The event, themed “Carbon Down Arizona,” included a selection of environmentally friendly vehicles. Representatives from car dealerships and several independent vehicle owners were there to show hybrid and electric vehicles.

The University of Arizona's electric Zap Truck was on display at the event. The UA purchased the truck to add to its fleet of electric golf carts.

“We have a lot of golf carts, and we wanted to do something sustainable,” said Kathy Sherrill, associate director of finance for the university.

The truck, which has multiple uses around campus, cost the university $16,000, Sherrill said. She talked about the benefits of the truck but noted two minor disadvantages.

First, it does not have air conditioning. “They had to put their own cooling system in,” she said.

The cooling system, which works like a swamp cooler, is hooked up to a cooler filled with water in the back of the truck.

Sherrill said the Zap Truck manufacturers claim it gets 25 miles before it needs to be recharged, but so far, Sherrill said, UA staff members have only been able to go 20 miles before recharging.

According to Tony Parker, fleet manager for Precision Toyota, people want to buy the Prius because they want to be green.

"We saw sales on the (Toyota Prius) double since the gas crisis hit," he said.

Along with the Prius, Parker brought the Toyota Camry to the event. According to Toyota's Web site, the Prius gets between 45 and 48 mpg, while the Camry gets between 22 and 33 mpg.

Though the Camry is also a hybrid option for buyers, the Prius is by far the better seller of the two, Parker said.

The Prius was introduced in 2000, and “in the last three years (sales have) doubled every year,” Parker said.

According to consumer reviews by Edmunds' New Car Research Center, however, some Prius owners have experienced "poor handling" and "poor gas mileage" compared to what they expected from the vehicle.

Used Car Conversion photo by Zack DiMaggio "This vehicle costs about 3 cents to operate," said Al Berry, who started driving a self-converted Ford Escort last August. "Driving this to work only costs about $200 a year, and my diesel truck costs upwards of $3,000," he said. Clean car conversion appeals to some car owners who would rather use their older vehicles than buy a new electric car. "I like the idea of retro-fitting existing vehicles," said Mark McIntyre, an onlooker of the clean car show. "It is a matter of scale. If dealerships began to do that, it would be a lot more efficient." — Erica Coleman

Chapman Honda also displayed hybrid and eco-friendly vehicles.

Fred Hall, fleet manager at Chapman Honda, demonstrated the 2010 Honda Insight and the 2009 Jetta TDI. The Honda Insight is listed at just over $25,0000. It hit the market last month, but “the first ones have already been sold,” Hall said.

The Insight features an economy button that controls features in the car such as air conditioning to limit the car's energy use. With the economy button on, Hall said, drivers can get fuel mileage in the “high 40's and low 50’s.”

Also on display was the 2009 Jetta turbodiesel, which runs on low sulfur diesel fuel. According to the JDPower Web site, it is among the most fuel efficient in its class.

“(The) Jetta is our most popular car. The turbodiesel is becoming a very large portion of the series because of its gas efficiency and because it's eco-friendly,” said Hall. “The Volkswagen buyer is generally more environmentally friendly.”

Instead of buying a new car to be eco-friendly, some drivers convert their existing cars to run on electricity.

Steve Conley converted his 1998 Chevy S10 pick-up truck, finishing his project in August after about two years of work.

“I like it quiet,” Conley joked. “It makes sense as I never go more than 20 miles. And I’m still upset about trying to get gas back in 1973 on North Campbell, waiting in line (to get gas) so I could get to work.”

He purchased everything for his electric truck on the Internet, and to him, the benefits were substantial.

“You don’t have to buy oil and you don’t have to give money to the oil companies,” Conley said.