Negative, they could even be built here (see the Saturn Ion, Saturn Astra, Chevy Cobalt, and Chevy HHR - those are all based of GM Euro designs, though not the ones they should have been based on, and were screwed up by the UAW with the exception of the Astra, which GM just imports directly from Belgium) so union jobs would be unaffected. That said, NOW they will probably be held up by government regs.
I know a couple of days have gone by, but I just happened to encounter documentation that government regulations prevent the importation of GM cars from Europe.
Background: Current Law
The “two-fleet rule,” established with the first corporate average fuel economy (CAFE) standards in 1975, divides each manufacturer’s car fleet into two separate compliance classes – domestic and foreign – based on where a majority of a vehicle’s parts are made. Each class must separately meet the 27.5 mile per gallon (mpg) passenger vehicle standard. The two-fleet rule for light trucks was eliminated beginning in model year 1996.
Originally, the rule was meant to protect U.S. auto jobs by preventing manufacturers from importing large numbers of foreign-made smaller cars – primarily designed for foreign markets with tougher fuel economy requirements – in order to meet CAFE standards. ......
.....The United Auto Workers (UAW) and domestic automakers, on the other hand, claim that dropping the two-fleet rule would cost U.S. jobs. They argue that the rule ensures that full-line auto manufacturers must maintain small car production in North America to balance out production of larger, less efficient
http://www.pewfuelefficiency.org/pdf/all-about-the-two-fleet-rule.pdf