Hi all, sorry I didnt see this come back to life sooner.
First off, we are now in month 8 and over 25,000 miles. Still runs and drives great, still probalby the best commuter use car I have ever owned.
My wifes car sits almost all the time now, she would rather take the Smart to the store or mall or whatever than her beloved Mustang Convertible (anyone want a deal on an 05 Mustang?)
Still averaging 43-45 mpg, toward the lower end with my commuting passenger, toward the upper end when its just me.
So far it has carried home a SBC engine, 2 sets of wheels and tires (not at the same time) a 43inch lcd TV....etc...so its alot more useful than it may seem.
As to the questions. Yes I run premium in it, and yes the milage deteriorates if you run regular, enough to make the extra cost of premium worth it. I've run other grades and Im pretty sure my wife always forgets to put premium in it. The performance is not effected but I do see a 2-4 mpg drop. Premium here has come back down in line with regular so its not a huge deal to me.
Yes extended warantees are available at most dealers, no I dont have one.
The "manumatic" is much maligned and wrongly so.
There are 2 issues
1) in the first 1000-2000 miles it shifts like crap and sadly most testers are driving new cars so that is their first and only impression. After 1000-2000 miles something happens, there has been debate wether the transmission "learns" or the clutch just beds in or magic gnomes suddenly appear but one way or another it does smooth out.
2) It never feels completely like an automatic because its not, its a genuine 5 speed and its got to shift between each gear. People who arent used to manuals find the feeling funny, but if you are used to them you will recognize it right away and as you would do with a regular manual you will lift off the gas slightly to facilitate the shift. But even without this behavior the transmission feels much better after the first few thousand miles and is not a weak point in my mind at all. I will admit on my first test drive it was wonky enough to make me rethink the car, but I decided to give it a shot and it was worth it.
And just so I dont sound like a complete fanboi, my dad is in the market for a new commuter and I've talked him out of getting a smart. Why? The warantee, he doesnt wrench on his own cars so he needs the warantee.