Well, you will be dealing with several issues here:
1. Must meet DOT standards i.e. KM to Miles speedometer, side markers, chasis serial number location. In Europe under the hood tag while in the US must see numbers through windshield.
2. Must meet EPA standards i.e Leaded gas Vs. unleaded must have catalyst converter however if the car is older than 5 years it will be waived.
3. Must pay US customs on vehicle. this is not to be confused with your state taxes at the motor vehicle in your home state. Custom Duties are paid to Washington D.C (federal customs) that is to say: certain percentage based on how much you paid for the car. your receipt will be the prove or your bill of laden issued by the shipping company.
4. Of course shipping from Europe can range from $1500-$2500 depending on the method of shipping. i.e. on top of the deck of the ship (salt, dirt grease, dents etc)or inside a container which better, cleaner and of course more expensive.
5. you will have to hire a shipping/customs broker at the port when the car arrives at the US port. This broker will post a bond on your behalf to make sure the car will be converted to US standards.
5. You cannot obtain a title for this car unless it is modified and the title will not be issued from those local MV agancies in your state. the first title will be issued at the main offices in the capital of your state, subsequest renewals will be normal.
6. All in all you talking $2000-$3000 for DOT modifications only, $3000-$5500 for Both DOT and EPA. remember you don't have to do EPA on cars older than 5 years.
7. They may or may notl impose a rule where you cannot sell the car for the first 2 years. New Jersey likes to do just that. Even if you sell the car the transaction will be rejected by DMV's computers for the first 2 years.
But this is what I would do since you going to be in France: jump on the train (are you in for an exciting ride? Ok then and make sure to ride the train called ICE. It does non stop trips to Germany at a speed of 300KM+ per hour; in fact it is white in color and hence ICE check it out on the internet!)
Assuming you do the trip to Germany when buying a BMW ask the sellers/dealers etc for a european car modified to the US specs in Germany, it will be ready and guaranteed in the US. have in mind that European BMW/Mercedes have different serial numbers than US cars ; this will elliminate parts problems at the dealers here, otherwise for older cars you will be forced to buy what they call gray market parts.
Of course you must double check the above info. with the appropriate agencies in your state. I went through the above procedures when I imported a car from Germany but rules and regulations are constantly changing so someone can get your money while protecting North American BMW. Good luck and let me know how you do. Have a safe trip.