I just checked with GEICO today and I was quoted around $250 for 6 months. It seemed like they don't insure Smarts unless you are already a customer and possibly been a customer for a number of years. I have 2 vehicles presently insured w/ them and have been a customer for more than 7 years with no claims.
I say this because when I asked if they insure Smarts, the response was, "Yes and no." The person then asked for a model or VIN # and my policy#. I was then put on hold for a few minutes, presumably to check my "record", she then came back and said, "We'll insure it for you." Like they were doing me a favor.