[crote]

The entire point of the European Union is to eliminate all of that friction. Most of the rules and regulations have been pushed to the EU level, just like the USA pushed most of its rules and regulations to the federal level. A car only needs a single type approval granted by a single member state, and it can be sold across the entire EU.

There are of course still some tax differences and importing from another member state might be slightly trickier for a consumer than buying it from a dealership in their own country, but I don't see how that is any different from dealing with different kinds of sales tax in the various US states, or having to transfer your car title to another state.

The European single market operates as, well, a single market.