Hello.
There wouldn't be one national database to check with here in the U.S. Each state maintains the records for varying periods of time of the cars registered in that state. What you would need to do is find out which state the car was registered in when it was purchased and shipped to Iceland. It would have had a title when it was shipped, and that title would have had a name and adress on it of the previous owner. Start with that person, see what he or she might remember about who they bought the car from, and just back-track it from there. 