I don't think the US is as important to the rest of the world in regards to automotive technologies and I don't say that to be rude. America has always had a very different type of market to Europe and Asia and American branded cars have always sold very poorly in Europe apart from Fords and Opels that are designed for the market here specifically. The regulations here are alot of more strict in terms of annual checks, safety testing and emissions and I'd say the German auto makers have the most influence over other brands and direction of standards than any other manufacturer.
The US is the #2 importer of German cars, number 1 being China...
The US has as strict, if not stricter Emissions than Europe does. In order for a vehicle to make it to the US as a new car, there are very heavy regulations on emissions testing. Our #1 state for vehicle sales, has an even stricter level (CARB).