We have IVA in the UK but it is mostly used to import Japanese cars at the moment because you only need a few modifications to most cars (fog lights, indicators) and the Yen is weak at the moment so a lot of people are importing cars like the Suzuki Jimny which meet our standards but aren't sold due to Europe wide emissions regulations. You would have to do a lot more to an American car because the safety standards are different so it isn't an attractive option unless you really want a specific vehicle at any cost.