They're only a quarter of the way to the finish line but the organizers of the “Two Million Mile Haul” feel their field-documentation study on the benefits of running a 20% soy biodiesel blend (B20) in a fleet of trucks is already smelling like roses.

The main backer of the Haul is the Iowa Soybean Assn. (no surprise there). The association has partnered with Iowa Central Community College, Decker Truck Line Inc., Caterpillar Inc., the National Biodiesel Board and the USDA to conduct the study.

I don't know about you, but soy has always been something of a mystery to me. I know it it's used to make a great sauce for Asian dishes and now it can be used to make trucks go. Who knew?

Wikipedia tells us the soybean is a legume (bean) native to Eastern Asia. The bulk of the crop is solvent extracted for vegetable oil and defatted soy meal serves as animal feed. A very small proportion is consumed directly as food by humans. But soybean products appear in a large variety of processed foods - and can be blended into biodiesel fuel.

As for the ongoing Haul, Iowa Central Community College handles collecting and analyzing engine performance data as well as periodic in-house testing of the petroleum and B20 blend fuels for purity and consistency. The study is also examining the effects of various fuel additives on the cold-flow properties of biodiesel blended with 2007-spec ultra-low-sulfur diesel (ULSD), focusing primarily on the cloud, plug and pour points.

By April, Decker Truck Line had logged more than half a million miles in the study using 10 trucks in a control group (fueled 100% with #2 diesel) and nine trucks in the B20 test group (fueled with a blend of 20% biodiesel).

According to the Iowa Soybean Assn., it's been determined that “driver-to-driver variability in fuel consumption within each group is two to three times greater than the overall difference in fuel consumption between the two groups.” Furthermore, the results showed a “slight decrease in fuel efficiency in the B20 group through the winter driving season.” Average fuel consumption for the control group was 6.01 mpg, while average consumption for the B20 group was 5.80 mpg, or a 3.5% reduction. However, it was stated this value is not statistically significant.

It was reported that winter driving produced relatively few problems regarding cold-flow issues. Fuel for both groups was treated with a commercial fuel additive and #1 diesel (40% blend) was used briefly during a severe cold snap. No fuel-gelling problems were incurred.

The study's researchers regard the first quarter of the Haul a success as they found no significant difference in fuel consumption between the two groups and were able to get through a winter without any major complications. There were no fuel gelling problems seen during cold snaps and the plugged filters that did occur were not related to fuel quality as outlined by ASTM-D6751 standards.

The Haul thus far has demonstrated that “driver-to-driver variability is larger than the slight difference in fuel efficiency observed to this point and an entire four-season driving cycle should be completed before conclusions can be made on fuel efficiency.”

That makes sense. And judging by the positive results of the Haul so far, it may be high time to tell the next person who tries to feed you tofu that you'd rather have your soy in your diesel, thank you very much.

For more on the results of the Two Million Mile Haul, go to:

For more on ISA, go to