Gas tank information can be found here:
https://aftersales.i.daimler.com/ser...2007_en_72.pdf
See pages 146, 149, 150.
"Location of fuel tank:
The fuel tank is located in the area in front of the rear
axle on the smart model series.
The fuel lines run in protected areas and are made of
plastic. In the engine compartment they are routed so
that in the event of a deformation of the body structure
as a consequence of a frontal or rear-end collision,
the fuel lines cannot normally be ripped off.
The fuel pump is automatically switched off if the
airbags are activated or if the engine switches off."