Hi,
It really depends on what 'kind' of car it is. If it's a car that has the exact same model here in the UK, then it's not really worth bringing over. If it's something 'interesting' then it quite possibly could be worth bringing it across!
The lady Cheers refers to was 'incredibly' attached to her modern VW Beetle and had the funds to bring it over, so in that respect, I can understand going through everything to do so even though there's lots of the modern VW beetles already here. The process isn't a nightmare really, just quite a lot to do and sort out. I have my eye on a few US cars I want to import again to here and I'm not too worried about sorting it all out.
It sounds as though you'd be better off selling your car over there for whatever you can manage to get for it. The shipping cost depending on if you are East Coast US or West, or perhaps in the Southern states is likely to be at least a couple thousand US dollars, and costs to make the car road legal here, approved and tested as well as any duties and taxes (probably fairly minimal) will also add significant amounts. Cost of insurance varies, and although the general consensus on this forum is that it'll be 'expensive' is quite accurate, it's not by any means absolute - there's some excellent car insurance deals around. As your car has a rebuilt title, this is the most important reason for selling it off within the US, if upon arriving here and during the test to ensure it's roadworthy for the UK it fails, then it'll not be allowed on UK public roads and you'll have a next to useless car here.
Cheers, DtM! West London & Slough UK!