There is a mountain of reasons which are interlinked together as to why diesel passenger vehicles are not prevalent in the USA.
I suspect that one of the reasons is government policy on choice of fuel for security reasons.
If the entire nation was very dependent on one type of fuel, and there's some kind of worldwide supply glitch, this could cause the entire country to go into shutdown. Let's say for example that USA and Europe both are very dependent on diesel fuel - and let's just say that something caused the diesel supply to be halted temporarily.
Two major regions of the world would no longer have functioning transport systems.
From an external person's point of view, the systems that are used in USA are different to Europe, and from an initial perception point of view, they seem to be deliberately different.
If you had to apply for a VISA to the United States, your passport photo must be of square dimensions, but the rest of the world is rectangular. The rest of the world seems to have standardised on GSM as a mobile phone comms protocol. USA uses something different, again, probably in the interest of national security.
Metric measurements in Europe, feet and inches and gallons in USA.
I'm sure we can start a whole new thread on what's different in the USA compared to the rest of the world. Just about every major standard or code of practice used in the USA is different to the rest of the world.
Some of it could be due to protectionism, but I suspect a lot of policies are set up for national security reasons.
That's my viewpoint, rightly or wrongly...
