MONTREAL - People were once incredulous when Dylan Perceval-Maxwell told them his car ran on the discarded deep-fryer oil he collected from fast-food restaurants.
But that was before the price of gasoline rocketed past 40 cents a litre, doubled, and finally blew beyond a dollar.
Now when the environmental activist talks about his green vehicle's savings on fuel, other motorists are keen to know how it works.
Advocates of vegetable fuel suggest it can shave more than 80 per cent off the cost of filling your tank, while reducing carbon emissions.
Perceval-Maxwell is among the small number of Canadian drivers who fuel their diesel engines more cheaply, and cleanly, with vegetable oil. He began experimenting in the early 1990s by pouring recycled cooking oil into the diesel already in his tank.
"I bought the cheapest car I could find and just mixed it in, and it works like that," he said.
"I wanted to drive a car and something that wasn't gasoline or diesel."
It might strike some as a novelty trend but the concept is actually as old as the diesel engine itself. In fact, German-French inventor Rudolf Diesel originally designed his engine in the 1890s to run on peanut oil before that fuel became supplanted by cheaper petroleum.
The technique does have some drawbacks.
While diesel engines can run on vegetable oil, gasoline engines - which are more popular in Canada - can't. And some motorists with diesel cars might find the process a little more arduous than a simple stop at the gas station.
Perceval-Maxwell gets the oil from a restaurant close to his home and stores it in a 20-litre bucket rigged up to the engine of his Volkswagen camper van. At the end of the process, his vehicle winds up with a pleasant aroma.
"It smells like French fries," he said. "It smells a lot better than diesel fuel."
While he was motivated by environmental concerns - to find an alternative fuel that pollutes less than diesel - other drivers might make the switch to vegetable oil to save money.
Both types of customers turn to PlantDrive, a company in Salmon Arm, B.C., which sells kits for hooking up diesel engines to run on vegetable oil.
"Every time the price of fuel shoots up, we see a tremendous increase in interest," said president Edward Beggs, who founded PlantDrive in 2002.
PlantDrive's $1,000 fuel system captures the engine's waste heat, using it to preheat vegetable oil to 80-90C so that it can properly combust.
When the vehicle is turned on, it uses a bit of diesel until the engine heats up and then switches to vegetable oil. At the end of the day, the diesel engine runs again for a couple of minutes before the car is switched off.
The vehicle can also still run on diesel or biodiesel alone.
"So many people get the idea that, well, if I do a conversion what if I can't find vegetable oil? No, you just go to the diesel pump and fill up with diesel," said Beggs.
But the goal is to go to the pump as little as possible.
While there are wild estimates about how much the process might curb carbon emissions, it undoubtedly saves money.
Beggs used to spend $50 a week on diesel, but now he says he only fills his Mitsubishi van with that amount of diesel every month and a half. That suggests a savings of 82 per cent.
He estimates that between 5,000 and 10,000 Canadian drivers run their cars on vegetable oil.
"(But) it's not for everybody," he said. "I'll discourage people if I sense that they really don't understand anything about how the engine or the car works."
Like Perceval-Maxwell and Beggs, most of these drivers get used vegetable oil for free through arrangements made with local restaurants. They pick it up in jugs in parking lots and filter it themselves at home.
This practice is not taxed because it is not covered under the federal excise tax, said Canada Revenue Agency spokesperson Philippe Brideau.
In the United States, regulations aren't so clear-cut. They even reportedly tripped up California Governor Arnold Schwarzenegger, who owed road taxes for the vegetable oil burned by his modified Hummer.