The idea of "splash and dash" is that a very small amount of "petrodiesel" (just a "splash") is added, to make a shipload of biodiesel count as a "blend," so it qualifies for the "blenders tax credit."
http://www.csmonitor.com/2007/0608/p02s01-usec.htm …
Created under the 2004 American Jobs Act, the "blenders tax credit" was supposed to boost US production of biodiesel by encouraging US diesel marketers to blend regular petroleum diesel with fuel made from soybeans or other agricultural products. It succeeded, perhaps too well.
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Your editing left out the vital part:
http://www.csmonitor.com/2007/0608/p02s01-usec.htm …
If the ship holds roughly 9 million gallons, it takes only about 9,000 gallons of traditional diesel (0.1 percent of the total) to make the entire load eligible for the blenders tax credit.
The US importer of the load applies to the Internal Revenue Service for the credit – a dollar for each of the 9 million biodiesel gallons, Mr. Baize calculates. The next day the tanker can set sail – dash – for Europe. There, the US importer resells the biodiesel, taking advantage of European fuel-tax credits that, in effect, keep biodiesel prices above US prices.
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http://www.biodieselmagazine.com/article.jsp?article_id=1863&q=&page=all …
European Union (EU) countries started to notice biodiesel being imported as a B99.9 blend. That is, about 1,000 gallons of petroleum diesel were added to every million gallons of biodiesel. That small “splash” of petroleum diesel, if added to a tanker of biodiesel from, for example, Malaysia, in a U.S. port, would qualify the entire shipment for the U.S. tax credit. After getting the credit, the tanker could continue to Europe—the “dash”—and receive European fuel tax credits. In effect, the fuel would be subsidized once by U.S. taxpayers and again by the Europeans.
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So, it's not that the tanker now holds a laughably small percentage of true "biodiesel" it's that it contains a laughably small amount of "petrodiesel." The blend is being represented as "B99.9" (99.9% biodiesel) which is what it is.
They're not conning consumers, they're taking maximum advantage of tax incentives.