Via the Alternative Fuels & Advanced Vehicles Data Center:

A new specification for biodiesel fuel blends have been published by ASTM International. ASTM D7467-08 covers biodiesel blends ranging from B6 (6% biodiesel, 94% petroleum diesel) to B20 (20% biodiesel, 80% petroleum diesel). The new specification reflects years of research into the properties of biodiesel blends and how those fuels affect engine performance.

ASTM has also approved some updates to the existing standard for pure biodiesel (B100) designed to control product quality prior to blending with conventional diesel fuel as well as for diesel fuel oils used for on- and off-road diesel applications.

According to Bob McCormick, principal engineer for Fuels Performance at the National Renewable Energy Laboratory (NREL), "NREL has conducted extensive research over the past four years to support development of these standards, which we believe will lead to an expansion of markets for biodiesel while at the same time ensuring that users have trouble-free performance."