ASHEVILLE, North Carolina (CNN) -- Greg Melville's neighbors in Vermont looked at him like he was crazy 2˝ years ago when he drove what he refers to as his "vegetable vehicle." It's a car that runs on vegetable oil instead of gasoline.
Greg Melville converted a 1985 diesel station wagon to run on vegetable oil when his family needed another car.
Back then, gasoline cost about $2.20 per gallon. Now that the cost of gas is nearly twice that, many Americans are starting to think that converting to a vehicle that runs on vegetable oil isn't such a bad idea.
Melville, who now lives in Asheville, North Carolina, says the decision to convert a 1985 diesel station wagon to run on vegetable oil came about when his wife was in medical school and the couple needed a second vehicle.
"We did some research and found out that the old Mercedes engines were very easy to convert, just because they are practically indestructible," Melville explained.
After he found a good deal online, the couple purchased the car and found a conversion kit from a company in Massachusetts called Grease Car. The Melvilles then took the car and kit to an expert installer in their area and in no time, they were driving around -- with free fuel.
The kit and installation cost about $1,000 each, and Melville says it took about 1˝ years to recoup that cost.
"We're kind of playing with house money, because we're driving on free gas, and it's paid for itself many times over," he said.
Melville, who is a writer, has driven the gas-free vehicle more than 60,000 miles, including two cross-country trips he's written about in an upcoming book. Veggie car makes a cross-country road trip »
The converted car was outfitted with a 15-gallon tank. Melville says it gets about 20 miles per gallon, the same fuel economy it would have gotten with the original diesel system. But according to a recent editorial he wrote for The New York Times, Melville says his carbon footprint is cut in half while driving the car fueled by vegetable oil.
But all is not golden -- or green, as the case may be -- in this veggie tale.
Melville admits that there are a few downsides to having a vegetable-oil powered vehicle. The process of collecting and filtering the grease can be time-consuming and a bit messy.
He's made arrangements to get most of his waste oil from local restaurants, and each week, his suppliers leave him five-gallon drums that he must pick up. But when he travels long distances, he has to find new restaurants on the road that are willing to give him their used grease.
Once Melville gets the grease, he pours it into a large gas can that's been painted black. The dark color helps absorb the sun's rays, which heat the oil inside. The process helps thin the grease and makes it easier to filter bits of onion rings and other fried foods.
"[It's] not always the cleanest thing. I've spilled it all over me a couple times," Melville said.
Another side effect of using vegetable oil is the smell. The undeniable aroma of french fries and other deep-fried foods wafts up frequently from the exhaust. Depending on a person's palate, the aromatherapy could be a deal-breaker or a fringe benefit.
Still, Melville says he would recommend a vegetable vehicle to anyone -- with the following caution:
"Make sure you have a supplier lined up, because suppliers are becoming harder to find."
Even though many Americans love to eat fried food, there's not enough leftover oil to power all of the cars in the United States. The vegetable-oil powered cars have become so popular, there have been reports of cooking oil thefts from eating establishments across the country and talk of restaurants charging for the leftover oil.
For now, Melville isn't concerned.
"My hope is ... by the time that happens, some other alternative like plug-in hybrids will come along and make these cars obsolete," he said. "Then I won't have to be filling it up with vegetable oil, and I can have a plug-in hybrid and go to a regular gas station and not have to feel guilty or worry about it."