From and electrical point of view there should be no problem (assuming
american cars use a 12v negative ground system) you might need to do a
bit of rewiring from the plug, however it would surprise me if the
cars in america used a different wiring layout because they would then
have to use 2 different manufacturing lines for the same system. I
could well be wrong tho.

If you are looking for a good mp3 system and dont want to take the
chance of buying that one and being wrong, i would recommend the
pioneer DEH7600, its fairly cheap and the sound quality is tremendous,
the only drawback is that the convertor for you steering wheel stalk
is quite expensive