re: Why can't we get a compact, 4 cylinder diesel pickup here in the US?

My very limited understanding of the situation is this:

25% import tax on light trucks dating back to the Johnson Administration, AKA the Chicken Tax

American manufacturers fear light duty trucks would harm one of their most profitable products, the Class 2 Light Truck (F-150, Silverado 1500, Ram 1500).

EPA Emission Standards for diesel-powered vehicles are stricter than other countries that manufacture or import light trucks.

American manufacturers do have not shown a commitment to R&D for a diesel-powered engine which would meet or exceed EPA emission standards in a light truck smaller than their profitable products.

It would appear the Big Three could lobby for reducing emission standards to start producing diesel-powered light trucks but there is a fear that the foreign manufacturers (Toyota, VW, etc.) would dominate the US domestic market because the foreign manufacturers are far ahead in R&D and could commit to manufacturing plants in the US faster than the Big Three.

I expect someone to refute some or all of my thoughts, and encourage others to bring more information to the discussion so we can better understand why the light, compact trucks so popular around the world have not and are not available in the US.