Of all the states that BO lived prior to Illinois, which has the cheapest car insurance? Look there. He probably just maintained and out of state license until he absolutely couldn’t any longer.
The first time we see of Obama and the automobile is this:
Jerry Kellman, who hired him as a community organizer for the Developing Communities Project (DCP) of the Calumet Community Religious Conference (CCRC) in Chicago, and is now a strong supporter, says it was "$10,000 a year and a $2,000 car allowance". Obama himself has given different numbers; his memoir says $10,000 (as well as the car), in his "Wesleyan speech, he gave it as "$12,000 a year plus $2,000 for an old, beat-up car", and when he announced his candidacy for president, it was "a group of churches had offered me a job as a community organizer for $13,000 a year".