Ask US carmakers for turbo-diesel versions like those they sell in Europe

GM, Ford, Chrysler car models sold in Europe or South America have same body as US models but much more fuel-efficient and clean engines than US.
Turbo-diesel versions are common abroad and go up to 50-60 mpg.What's stopping US car makers to start selling same models they sell in US today but with turbo-diesel engines like the ones they make in Europe?I'm not saying to outsource our labor. I'm asking: bring those engines blue-prints in the US and start making them here for US cars. We need them now. It's a tested technology and better than hybrids. We can't wait another 5-10 years. Thank you.
45 mpg: http://media.ford.com/article_display.cfm?article_id=2720341/56 mpg: http://jalopnik.com/356497/hypermiling-the-2007-honda-civic-22-i ctdi-and-2007-audi-q7-42-tdihttp://www.greencarcongress.com/2005/09/gm_unveils_opel.htmlhttp://www.chrysler.it/grand_voyager/features/performance/index.html