Here's my two cents worth about how the totally weird smart fuel gauge works.
It's poorly worded in the manual, and, in my opinion, different than any other car on the road. The gauge reads 0.0 when there is still a substantial amount of fuel in the tank. Every other car I've owned has a gauge that reads Empty when the tank is near empty.
And, every other manufacturer clearly and unequivocally states the total quantity of their tank. smart has made the mistake of having a pseudo "reserve" in the tank, which is really just the approximately 1.3 gallons remaining when the gauge reads 0.0.
One of the unintended consequences of this is that virtually every reviewer, and even the US Government on the fuel economy website, thinks the range of the car is 8.7 gallons X (whatever mileage they use). This makes the range of the car seem very short in comparison with others. With every other car on the road the range is calculated on the total tank capacity. With the smart, it's based on a partial tank capacity.
Some may continue to disagree about the total tank capacity, but it seems clear, at least to me, that the tank is well over 8.7 gallons and is most likely 10 gallons based on the smart techs and dealers and the users here who have pumped in more than 9 gallons.
BTW, today I put in
9.4 gallons after running for 30 miles beyond the 0.0 on the gauge. I didn't use a bad pump. I didn't fill to overflowing, I didn't jack the car up on one side. I just filled it the same way I always do.
If I were the smart tech writers I'd rewrite the manual to say:
The total tank capacity is 10 gallons. The gauge bars indicate the quantity in the top 8.7 gallons, and the countdown gauge starts when 7.7 gallons have been used. When the countdown gauge reads 0.0 there remains approximately 1.3 gallons of fuel in the tank.
Here's how I think the tank works:
Hope to see you at Redhook! Printed out the menu last night.......can't wait!! I'm into eating, as you can tell from the photo of me next to my smart e!! 
Just remember in the future though.........keep repeating.........."It's always raining.......it's always raining..........it's always raining!! 
Today
Linear Mode
