The 2008 uses a completely new Emissions system which is designed to run up to 100% Biomass GTL fuels "BTL". These fuels are 100% synthetic BUT 100% renewable produced completely from Biomass (anything carbon based which can be grown).
Running older non-synthetic bio fuels (aka 1st Generation Biofuel) results in a fuel that lacks uniformity in terms of how it will burn in these motors. Because of this lack of uniformity and "unknown" factor the risk to the emissions system is too great.
Whether VW will allow up to a 5% addition of 1st gen fuels (Biodiesel) is yet to be seen.
The BTL producers are multiplying rapidly and the availability is increasing all over the world. Here in the US demand is simply not there due to the small percentage of diesels relative to gasoline engines in addition to the low cost of fuel/gasoline.
If our fuels were to cost $7.00 a gallon as is the case in other countries we would probably be ramping up production of these synthetic fuels.
The transition to synthetic fuels holds a LOT of promise here because they can use other sources such as natural gas and coal which the US has enormous supplies of.
In the mean time and until BTL arrives ULSD is our best solution.
There are many programs afoot. One involves DaimlerChrysler, Volkswagen and the Freiberg, Germany-based Choren Industries GmbH who are in a cooperative effort producing synthetic BTL diesel fuels in small quantities right now. They are producing it initially from waste wood acquired from forest management. The effort first began with DCX and Choren, but Volkswagen is now fully aboard.
DB