Attempting to drive to Los Angeles and back in an old car with over 330,000 miles (the odometer has stopped countless times over its life, so true mileage is probably above 350,000) and with a recently-converted fuel system designed to burn waste vegetable oil is asking for trouble. But I like a good challenge.
My first and biggest mistake: hot-filtering my oil. I had over 100 gallons of waste vegetable oil to filter through 20 micron sock filters in one weekend. I began pouring the freezing cold goop (Atlanta was down in the 30s that week), and it simply sat in the filters, barely dripping through. So I microwaved the stuff, two gallons at a time, and it flowed through beautifully. But what I didn't know was that this was allowing waxy parafins to pass through - parafins that would soon clog up my inline fuel filters all the way across the country. Needless to say, a few hours of panic followed by countless roadside stops and filter purchases at NAPA, Autozone, and Pep Boys across the country were needed. And yet - with over 100 gallons of nasty, improperly-filtered vegetable oil - I made it to Los Angeles. Indisputable proof of the indestructable nature of Mercedes diesel engines.
Veggie Across America: hypermiling downhillEnlarge Photo
Another notable dumb move: not planning out my fuel stops on US 40 while driving through some particularly desolate mountain areas in the West (I didn't have time to collect the needed amount of vegetable oil for the drive home while in L.A., so I just used diesel #2 instead, which the engine will still happily burn). With the notoriously unreliable fuel gauge reading half empty, I figured I'd just drive 'till empty and then pull into a Chevron (I'm one of those guys - let me see how far I can get on this tank!). Except that on this particular stretch of 40, there wasn't a gas station that offered diesel for over 100 miles. I discovered this unfortunate fact only after I was miles beyond the last diesel station, so I decided to just press forward and hope.
1982 Mercedes-Benz 300TDEnlarge Photo
Of course, this drama occurred on an occasion where my fuel gauge was lying - it quickly flicked down below 1/4 tank after I climbed the first fuel-sucking grade up a mountain. I got that panicky, sick feeling in the pit of my stomach, fearing I might soon find myself stranded. It was high time to experiment with hypermiling. Luckily, diesel engines are extremely efficient at small throttle openings; I put the hazards on and didn't exceed 45 mph on flats and uphill grades. Downhill, i put it in neutral and just let it idle (another situation where diesels use miniscule amounts of fuel). I even tried the ill-advised drafting trick on the flats, where one inches up pretty close behind a huge truck to take advantage of a small wind-free zone, further decreasing consumption.
I finally coasted into a gas station, engine still idling happily. Upon filling up I realized that I had about 1/4 gallon left in the tank. Wow. The force - and perhaps the magic of the three-pointed star - were with me that day.
Veggie Across America: hypermiling at sunsetEnlarge Photo