The Fuel gauges and EMIS works properly. I guess the problem is: Fuel Capacity.
Real Mirage fuel capacity is 122 gallons (120 usable), but If you set full tank, it will fill with 152 gallons.
Check page 16: http://www.rebay.at/fliegen/manuals/pa46_350_manual.pdf
I changed the Aircraft.cfg to the correct value, from 75 to 60 Usable gallons.
[fuel]
LeftMain = -1, -4, -1, 60, 1 //Longitudinal (feet), Lateral (feet), Vertical (feet), Usable(gallons), Unusable (gallons)
RightMain = -1, 4, -1, 60, 1 //Longitudinal (feet), Lateral (feet), Vertical (feet), Usable(gallons), Unusable (gallons)
I reported this to Carenado, they are aware of this and the other issues already mentioned above and will include in the Service Pack.