I went through
Classic Motorcars International to get my Lupo. Erik was a friend of a friend who took good care of me. He does a lot of car imports for people and is very familiar with the process. I will say bringing cars into the country is a difficult, time consuming, and costly proposition. It's much easier and cheaper to bring parts in as long as you know what parts you want.
The Smart diesel would be one way to go. You can source them from Canada which would be more convenient than going through the Europeans. It's a turbo charged 0.9L but based on my experience, you want the turbo charger for automotive applications. They make the engines much more responsive and efficient. With a turbo you don't need to carry as much displacement to get the performance you need to keep the vehicle from being a hazard to yourself and others.
The Lupo cost me about $8k when all was said and done. Erik can point you to all the forms you'll need to fill out if you'd like to import a vehicle. The primary agencies you'll have to deal with are: 1. EPA (always fun) 2. Federal Department of Transportation (even better) 3. US Customs. No. I didn't have a lawyer and I'm not a lawyer so I had to get good and reading/interpreting federal regulations.
Not a nuisance at all. Here's a build
photo album to give you an idea of what the swap was about.
Best wishes,
Jake