Here's the rub.
North American emission standards that exist for new diesels, coupled with variations in fuel quality across the nation will keep us from having a solid small diesel until we get some serious new technologies pounded out.
We aren't going to get Euro spec diesels here. Look at the way the emission windows get skewed for North American, European, and Japanese markets. The windows are very similar, just skewed enough that vehicles from one market can not be used in another. This is as true for gasoline powered vehicles. The windows for the different markets don't match for paticulates, NO, or CO.
Diesel EGR, EGR cooler, Particulate filter. Many folks that deal with these parts are having maintenance issues.
Not that the average guy treats a vehicle with maintenance in mind. Beyond an oil change and the odd wiper blade, most folks seem content to turn the key and drive 'till something goes wrong. It's rare to find someone that has actually opened up the owners manual and read it.
The Fed wants these vehicles to go through their expected life without a change in emissions while suffering little or no maintenance; the norm.
It's expensive for a manufacturer to do that, especially with the moving target that emissions requirements present year to year.
European vehicles do not meet North American standards for emissions, lighting and, in some cases, safety. It's all in how you hold the measuring stick.
Until those measures are standardized between the markets, we can't expect to have like vehicles or components.
2¢
CJ