Vehicle manufacturers have developed new vehicle and diesel engine technologies compatible with B6-B20 biodiesel blends meeting ASTM D7467, “Standard Specification for Diesel Fuel Oil, Biodiesel Blend (B6 to B20).” However, recent U.S. market place fuel surveys have shown that many retail biodiesel samples are out of specification. A vehicle designed to use biodiesel blends is likely to encounter occasional use of poor quality biodiesel fuel; and therefore understanding the effects of bad marketplace biodiesel fuels on engine and fuel system performance is critical to develop durable automotive technologies. The results presented herein are from vehicle evaluation studies with both on-specification and off-specification bio-based fuels. These studies focused on the performance of fuel injection equipment, engine, engine oil, emissions and emissions system durability. Evaluations were conducted on B-20 (20 volume% blend of biodiesel in ultra low sulfur diesel fuel, (ULSD), biodiesel (B100) and a 50 volume% blend of vegetable oil and ULSD. The study results showed that in general B20 fuels meeting the ASTM D7467 specification did not cause any operational issues but vehicles operated on off-specification biodiesel fuels experienced operational issues including internal injector deposits, combustion chamber deposits, sticking of piston rings and fuel filter clogging.