"Capt. Geoffrey Thorpe" The Sea Hawk at wow way d0t com wrote:

Small diesels give about the same fuel economy as hybrids, but the
diffuculty is making the tailpipe emission standards in the US -
particularly California. Thus the popularity of hybrids in the US but
not in Europe where emission standards are easier.

Actually, the emission standards are tighter in Europe. The reason they
can meet their emission standards with diesel engines is that they mandated
low sulfur fuel several years ago, and it is has an even lower sulfur
content than the ultra low sulfur fuel recently mandated in the US.

Where sulfur enters into things is that it fouls catalytic converters. By
eliminating the sulfur, converters can be used in the exhaust system to
reduce the amount of NOx and particulates, which are the two primary
pollutants from diesel engines.

Now that we have low sulfur fuel, a number of European manufacturers intend
to export their diesel car technology to the US. Expect to see new diesel
models that will even meet California standards, from companies like VW in
the new year.