Not true. Biodiesel emissions are extremely low, and lower in most categories than the emissions of gasoline powered vehicles. Additionally, given similar displacements, diesels will use less fuel per mile, and total output of pollutants will be less as well. With new emissions standards imposing similar limits on both gasoline and diesel engines, the emissions argument against the diesel engine is simply bogus.

Diesel-fued, biodiesel engines are a necessary part of the mix to any near-term solution to cleaner skies and energy independence, as they are far more versatile than hybrid-gas designs. You can have anything from a vegetable-oil powered VW Lupo getting 90mpg to a double-tractor trailer running soy B100. Four-seat hybrids can only supply a part of the vehicles required for national use. They can't carry any sort of load, nor can they serve as tow vehicles, full-service ambulances, work, police or emergency vehicles nor pull semi-trailers of cargo.