Biodiesel has no sulfur, so less particulate emissions than regular diesel. However, that doesn't help reduce the NOx emissions, unless the car is fitted with a more efficient emissions control system that reduces NOx emissions more (this won't be done for on-road diesel engines in the US until 2007, when ultra low sulfur diesel fuel for on-road use is required -- kind of like how catalytic converters for gasoline engines did not appear until 1975, when unleaded gasoline became available). NOx is the main problem for diesel engine cars under CARB emissions limits; although diesel fuel in California is considerably lower in sulfur than in other states, car companies cannot really depend on that, since California registered cars may be driven out of state on trips or whatever. The good news for diesel engines is that they tend to produce very low amonts of carbon monoxide and hydrocarbon emissions, the two main problem areas for gasoline engines.RSnyder said:Are we sure a TDI purchased in the US is cleaner than a Prius while running biodiesel? My understanding is that the high sulphur in US diesel fuel prevents VW from using the more efficient emission control system (catalytic converters and particulate filters) that makes the TDI tolerably clean. Without these, I think the TDI, even running biodiesel, puts out huge amounts of allergy causing particulates (soot) whenever the load changes on the engine. But I haven't checked in a few years.
It comes with glow plugs for starting. Although if the fuel gels in the tank, the glow plugs won't really help.Also, what's the usual solution to the gelling problem of biodiesel in cold weather? Does the US version of the TDI come with some sort of fuel preheating system? I guess this wouldn't matter on the west coast.