There's something about a vintage W126-bodied S-Class Mercedes-Benz that to me says, "Third-World dictator." I recall the revolutionary Bruno Sacco-designed W126s with a certain degree of fondness. In the Eighties, when I owned a mobile electronics store in New Jersey, they were a cornerstone of the business as they were often targets for radio thieves. We joked about the fact that some owners belonged to the "radio of the month club."

Last week, after reading Joshua Tickell's book From the Fryer to the Fuel Tank, I became intrigued about the prospect of buying a Mercedes-Benz diesel and running it on biodiesel or even straight vegetable oil. As there were several diesel-powered Mercedes for sale locally, I decided to check one out that initially caught my attention: a 1982 Mercedes-Benz 240D for sale in nearby Oceanside, California, offered for sale by Advanced Diesel Vehicles with a three-stage vegetable oil heating system installed.

When I met up with Mike from Advanced Diesel Vehicles, he was working on his next listing, an Eighties'-vintage 300SD -- a top-of-the-line S-Class. Ironically, the smaller 240D that attracted me in the first place was no longer available (the auction ended a few hours later with the bidding reaching $5,860) but Mike handed me the keys to the 300SD and off I went on a 20-mile test drive.

If you've never driven a W126 Mercedes, its most obvious feature is the huge steering wheel dominating the interior. While this 300SD was not a low-mileage cream puff like the 240D, it started right up with the characteristic clatter of pre-direct-injection diesels. On this car the air conditioning and sun roof were inoperative--Mike clearly states this in his very comprehensive ad, leaving it to the new owners to make such repairs. I pulled away and then out onto the freeway where I merged into traffic.

The first thing I noticed is that acceleration is leisurely; this is not a 2008 E320 BlueTEC. But once up to freeway speed, in this case 75 mph at about 3,500 rpm, it was a quiet and comfortable cruise. Any S-Class from this era was designed and built like a bank vault and this one was no exception. With 147,000 miles on the odometer, this 300SD could be considered a low-mileage example--most of the other similar vintage 300SDs listed on eBay clocked in at 250,000 miles or more--as it had been driven an average of only 5,000 miles annually.

Upon returning the car, Mike and I talked about the fuel-heating process that allows a conventional Mercedes to run on waste cooking oil or straight vegetable oil. Mike's system, installed on all the cars he sells, consists of three elements: a coolant heat exchanger on the fuel supply line just before it enters the injection pump, an electronically controlled top-loaded heating element built into the filter's supply in- and out-lines, and several elements directly applied to the injection lines which are covered with a heat-resistant tape/wrap and insulated by their co-polymer heat-resistant covers. The heating elements are controlled by a switch installed on the center console of the dash. Mike also installs an additional fuel pump, which greatly helps the flow of the thicker vegetable oil through the fuel filter.

"Heating the vegetable ensures you will get all the benefits which include better mileage, increased engine longevity, more power due to better compression, and very low emissions." says Mike. "This is an ozone/environmentally friendly vehicle. If you choose to use waste vegetable oil you will have no fuel costs."

The conversions Mike installs allow you to run your car on conventional petroleum-based diesel, commercial biodisel, vegetable oil, or a combination of all three, all from a single tank. Mike indicated that mileage is about the same for all three fuels and is more dependent on good compression and in the case of vegetable oil, preheating it. 

Mike, who secures most of his Mercedes diesels at auction, typically converts three to four cars each month and while he could retro-fit his system to other diesels, he chooses not to at this time. The components take more than 10 hours to install on each vehicle--the quality of the installation appears flawless--so he's concentrating on the cars he offers for sale on eBay. He says that cars like the five-cylinder 300SD that I drove, after his modifications, will typically deliver more than 30 miles per gallon at freeway speeds, while the smaller, four-cylinder 240D models will often top 40 miles per gallon.

While we were talking, he said that the 240Ds will sell in a price range between $4,000 to $6,000, born out by the fact that the 240D ultimately sold for $5,860, the high side of the range. His past experience with the larger 300SDs is that they typically sell in a range of from $5,000 to $8,000 with $8,500 being the highest price he's received. All his auctions are no-reserve and start at $200. He did note that there are several other vegetable oil specialists selling Mercedes-Benz diesels on eBay. (On eBay, search "Mercedes + diesel" then narrow down your search to just cars to check out currently available inventory. Vegetable oil-friendly previously owned diesels are also available from Audi, BMW, Lincoln (who used a BMW turbodiesel in 1985 on about 500 units), and Volkswagen.)

Speaking of vegetable oil, Mike says that five-gallon containers of cooking oil run about $27 at Costco. Coincidentally, it seems that the price of cooking oil seems to keep pace with that of petroleum diesel. Mike says his cars will also run on used transmission fluid, which he said is great to clean the injectors.

The operational economy of his cars comes when you can secure a supply of used cooking oil. Because of the interest in using vegetable oil as a fuel, restaurant owners, who used to give it away, now have commercial services who pay them to collect the grease, which is recycled. But if you're lucky you may find locations that still give it away. In any event, Mike noted that he can supply information on filtering the supply you secure. And yes, when following behind a car running a either a mixture or straight vegetable oil, you can get a distinct whiff of French Fries or donuts.

I find Mike's entrepreneurial spirit infectious and am fascinated by  the whole concept of using recycled cooking oil as a part of a larger solution to our dependence on imported oil. Having driven many high-performance diesel cars on past trips to Europe, I know of their potential. The problem is that here in the U.S. we think that diesels are either smelly polluters or unreliable based on the diesels that GM sold in the Eighties. Both are misconceptions.

Here are some statements and statistics from Joshua Tickell's 2003 book to think about:

• The Unites States consumes 125 billion gallons of gasoline and 60 billion gallons of diesel fuel each year.
• The United States generates 3 billion gallons of used cooking oil each year, which equates to 5% of domestic diesel fuel use.
• Each year 60 million acres of cropland are left fallow in the United States, much of it subsidized. If planted with rapeseed, which produces 100 gallons of oil per acre, the United States could grow up to 6 billion gallons of vegetable oil, 10 percent of domestic diesel demand. When combined with the refinement of used cooking oil, this could theoretically provide up to 15% of our diesel fuel needs. Mr. Tickell believes that this wouldn't impact food prices but I suspect that wouldn't be totally true; cultivating this much additional land has to have some sort of negative impact as there is only so much farm infrastructure in place. Farmers will grow the crops that bring the biggest return.

But where Mr. Tickell sees the real potential is producing fuel from algae; the most efficient biological producer of oil on the planet. The National Renewable Energy Laboratory (NREL) has concluded that 490,000 acres of land--less than 1% of land left fallow each year--could produce 10 billion gallons of oil annually (another 15% of domestic demand) and with economies of scale in production, would cost about about $1.65/gallon. While the pragmatist in me questions such pie-in-the-sky numbers, thinking that if it was so easy to convert algae into oil we would already be doing so, it would seem that we might be able to grow our way -- before we can drill our way -- to energy independence. (Available carbon dioxide to power the process is but one technological hurdle.) But our experience with ethanol gives me pause as there will probably be some unintended consequences of such a program.

Solving our energy needs will take a multifaceted approach, and driving diesels powered by grease is just one small part of the equation. We need a comprehensive plan, one that will allow the United States, which uses a disproportionate amount of the world's energy, to go farther in producing at least as much as we consume.

Ultimately, I don't think that I'll be bidding on Mike's 300SD. It's not because it's not a great car. It's just that he has a 1979 300TD wagon coming into his inventory, similar to the one pictured here. Let's see... a classic Mercedes wagon that runs on diesel, biodiesel, or vegetable oil, with all the versatility that a station wagon offers; now that's a compelling proposition that makes sense to me.

Resources

• From the Fryer to the Fuel Tank, Part One
• Green Daily: Fill Up For Free
• Awake at the Wheel: The Blog for Biodiesel Drivers
• Vegcar.net: Run Your Car on Used Cooking Oil

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