Are grease cars legal?

Waste vegetable oil is clean and efficient. It's just not exactly legal. See pictures of alternative fuel vehicles.
Image courtesy of Borough of Westwood, NJ

­With so many states ­implementing pro-hybrid-car measures, like close-up parking spaces, fast lanes and tax deductions, you'd think the government would encourage people wholeheartedly to drive vehicles that use even less gas than hybrids do. That's what most grease-car owners have assumed, in any case. After all, grease cars are the height of fuel recycling.­

­These vehicles are diesel cars that have been converted to run almost entirely on new or used vegetable oil. Conversion kits basically add a second fuel tank and line to the engine. The original fuel tank and line carry diesel, which the engine uses on start-up, to warm the engine in preparation for the injection of the higher-viscosity vegetable oil (heat thins it out), and on shut-down, to purge the engine of remaining vegetable oil. Burning vegetable oil produces fewer emissions than burning diesel (or gasoline). It emits fewer particulates, no sulfur, and less carbon monoxide. And most impressively, it's carbon neutral: The vegetables grown to produce vegetable oil consume more carbon dioxide than is released when that oil burns.


Beyond environmental concerns, converting a car to run on grease is also fiscally advantageous. As of December 2008, a gallon of diesel fuel costs about $2.50 [source: EIA]. A gallon of waste vegetable oil, the stuff restaurants use in their fryers, costs about nothing. Restaurants usually give it away for free to anyone who wants it, because they would've had to pay to get rid of it themselves.

So grease cars must be highly regarded by government agencies, right? After all, they help to save both money and the planet. But as it turns out, they're actually frowned upon by both state and federal authorities.

In this article, we'll find out why people aren't supposed to be driving low-emissions grease cars, and we'll see how they might end up costing their owners money in the long run.


Untested: Waste Vegetable Oil

Since WVO hasn't been thoroughly studied by the EPA, it's not approved under the Clean Air Act.­
Since WVO hasn't been thoroughly studied by the EPA, it's not approved under the Clean Air Act.­
Image courtesy of Borough of Westwood, NJ


Vegetable oil is an example of a biofuel. A biofuel is simply fuel drawn from a renewable, biological resource, such as corn ethanol, biodiesel and waste vegetable oil (WVO).

Grease-car owners choose waste vegetable oil, or WVO, for their cars. They filter the food bits out of a restaurant's WVO, also known as fryer grease, to make it SVO, or straight vegetable oil, which won't clog car engines. Grease cars can also run on SVO purchased from a store, like a big jug of canola oil from Costco. But this method costs more than regular diesel, not less.

The problem with vegetable oil is that it's not approved by the Environmental Protection Agency (EPA) for use as fuel. It's not exactly illegal -- it won't land you in jail -- but it could get you fined.

Other biofuels, like ethanol and biodiesel, are EPA-approved. They've been researched and tested heavily by the EPA and are government regulated like any other fuel source. In terms of EPA approval, this means that the ethanol or biodiesel you can buy from a commercial seller is in compliance with the Clean Air Act.

The reason you're not supposed to use WVO to power your car is that it hasn't been around long enough for the EPA to test its environmental friendliness. And since people just get it for free from restaurants -- just go up to the delivery entrance and haul away some french fry grease -- there's no way to make sure it meets the requirements of the Clean Air Act, which includes strict rules regarding how fuel is processed. Greasers are just storing fryer grease in their garages, filtering it and filling up.

And what can the EPA do to you for running your car on what may be the most carbon-neutral fuel source in the world? It can fine you $32,500 per day [source: Montefinise]. The EPA could also charge an additional $2,750 for modifying the car to run on a non-EPA-approved fuel [source: Montefinise].

While the EPA might be investigating grease-car owners, they have yet to fine anyone for the offense. The same cannot be said for state government agencies -- but their beef with WVO isn't about environmental friendliness.

Untaxed Fuel

Grease-car owners in some states have been told they need to register as "fuel receivers," that's the same as a gas station.
Grease-car owners in some states have been told they need to register as "fuel receivers," that's the same as a gas station.
China Photos/Getty Images


While t­he Environmental Protection Agency is getting on greasers' cases for driving around on fuel that hasn't been sufficiently tested, states are worried about more basic concerns: namely, lost revenue.

The problem here, again, is lack of WVO regulation. Since used fryer grease is not a government-approved fuel source, there's no mechanism in place to tax it. What you pay at the pump when you buy diesel or gasoline is partly state fuel tax. It varies by state, but we could be talking about 20 to 25 cents per gallon of diesel fuel [source: Fletcher and Freeman]. States take in a lot of money -- sometimes more than a billion dollars a year -- in state fuel taxes, and that money goes to pay for things like road improvements and other essential infrastructure projects.

When someone converts a car to run on grease, the state is losing out on probably a couple of hundred bucks a year in fuel taxes. That's not much when it's just one person. But when hundreds or thousands of people make the switch, lower emissions also means significantly less revenue.

So while the EPA has thus far mostly let grease cars off the hook, states have not been quite so understanding. There are stories around the country of people being charged not only back taxes for the number of gallons of diesel they would have used, but also charging them to act as their own gas station. In at least two cases, one in Illinois and one in North Carolina, grease-car owners have been told they need to register as "fuel receivers," a designation usually reserved for companies in the fuel business. And to become a "fuel receiver," you have to buy a $2,500 bond up-front as a guarantee that you'll pay your taxes. Between that bond, back taxes and any related penalties for using an untaxed fuel, some people have found themselves owing thousands of dollars for driving a grease car.

Some states, though, are onboard with the move to carbon-neutral WVO. Pennsylvania and Arkansas, for instance, automatically exempt grease-car owners from those fuel taxes [source: Fuller].

The hope in the alternative-fuel community is that the action taken by Pennsylvania, Arkansas and others will catch on. Perhaps the biggest obstacle is a simple lack of infrastructure to deal adequately with waste vegetable oil as fuel. In some states, people can sign up to pre-pay fuel taxes when they make the switch to WVO -- but that requires an established system to collect and tag that money as WVO-connected, which many states are not yet set up to do. So grease-car owners who do try to pay their fuel taxes are stuck working within the framework set up for other types of fuels -- which is how they end up having to become commercial "fuel receivers" when they deal with a whole 10 gallons a week.

Related HowStuffWorks Articles

More Great Links


  • Fletcher, Kenneth R. "Going Green With a Grease-Fueled Car Lands Driver in Gray Area of the Law." Capital News Service. Oct. 8, 2007.
  • Fuller, Harry. "That veggie oil car could get you into trouble in US." Greentech Pastures. May 19, 2008.
  • Henderson, Bruce. "Driver ticketed for using biofuel." The Charlotte Observer. June 11, 2007.
  • Freeman, Huey. "State makes big fuss over local couple's vegetable oil car fuel." Herald & Review. March 1, 2007.
  • Montefinise, Angela, and Susannah Calahan. "Defiantly Fuelish on Veggie Oil." May 18, 2008.