In terms of fuel comsumption I can give you a steer from my experience.
I have a a 2003 ForTwo Cabrio Pulse and when I was driving 30 miles each way to work every day, I could get approx 330 miles per tank. That is around 45 mpg on various roads, but no motorway and very little dual carraigeway driving, ie a lot of medium speed and stopping.
If I was doing longer journeys and took care to keep the speed and acceleration down (ie approx 60 mph raher than 70 plus on motorways and under 3000rpm) I managed to get 417 miles from a tank. That is approx 57mpg. I think I used superplus fuel for this however.
Now I have had my engine remapped (and a K&N filter and 'delipped' intake)from 61 bhp to around 80-85 bhp and do city driving only, with a bloody set of traffic lights every 200 yards and no journey over 3 miles, I only manage 285 or so per tank, which is just short of 40 mpg.
If the new ForTwo is similar I would say a careful driver could manage 60 mpg on a good run. Not amazing but not bad. I don't know if it will appeal in the US, but UK owners often compete with themsleves and each other to see who can get the most distance on a tank and post the results on Smart forums.
I personally think they should have done something really radical and produced the 100mpg Smart car, but hey, the diesl is not far off and I like the 80 plus bhp 'the Red Rocket' produces!
Has anyone considered a remap yet?