The "technical details" that have delayed the launch are not on the basic engine components, but on the emissions systems (VW has been building diesels for a long time, so it should be reliable.) The problem has been that they can't meet our more-stringent air quality laws, and VW has failed a couple of times when they thought they finally had it dialed in. They will get there.
All diesels can run on
ASTM D-6751 bio-diesel ... but that's not used fryer oil from the local KFC. You'll see pumps with B10, B20 or up to B100 (that's 10% bio, 20% bio and 100% biodiesel) in the next few years. The biodiesel is blended with petro diesel.
Biodiesel can be made from food sources (chicken fat from slaughterhouses, soy beans, etc.) or from non-food plants (Hawai'i is installing their first algae farm to produce biodiesel). One major advantage of biodiesel over other bio-fuels is that it can be stored, transported, piped and refined using the existing infrastructure.
If the car companies can finally make them clean enough, and they think they can now, bio-diesel may be the best bet we have to get off foreign oil (with the possible exception of breakthroughs in battery technology).
