The mpg for the new smart is indeed between 35 and 45-ish.
On that basis there is no point at all in running a new Smart. As ever (like the VW Golf etc etc) the original concept has been lost and the weight has piled on.
In the UK, The mini VW Lupo came out but was as big as the original Polo. The Polo became as large, in fact heavier than a Mk1 Golf which was a superb car. And the Golf became a huge bloated tank which ended up with an optional 3.2 litre engine if required! The MK1 GTI had a 1600! The Lupo has been replaced with the Fox which is a big car! Shame as VW sold a mega efficient Lupo 3ltr. That had lots of magnesium and underbody aerodynamics to get the magic 100km's to 3ltrs of derv.
35 - 45ish to the gallon? That's pathetic. You can get a C1,107 type Eurobox that does 70ish mpg on diesel.
Saving fossil fuel? Don't make me chortle. I suspect SUV's are still flying out of Ford dealers with the V8 option merrily ticked.
I suspect true Micros such as the Isettas,KR's that were marketed in the US in the 50's were viewed as oddities. Nothing more. History repeats itself a la Smart..