Because keeping diesel cars away from the US market leaves them with a bit less competition.<p>American companies make some diesel cars in other markets (Ford, and GM with its Opel and Vauxhall brands) but they have a significantly smaller market share in diesels than in gasoline engines.<p>Easiest way to look at it is this:
<a href="http:&#x2F;&#x2F;www.statista.com&#x2F;statistics&#x2F;425324&#x2F;eu-car-sales-share-of-diesel-engines-by-brand&#x2F;" rel="nofollow">http:&#x2F;&#x2F;www.statista.com&#x2F;statistics&#x2F;425324&#x2F;eu-car-sales-share...</a><p>You&#x27;ll find Opel, Vauxhall and Ford towards the lower end of the table.