Turning the key to MAR the warning light on the dial turns on, but it should go off as soon as the engine is started.
If the 
warning light turns on when
the car is travelling (on certain versions together with the message on the display),
stop the engine immediately and contact a Fiat Dealership.
See also:
10. Cruise Indicator — If Equip
This indicator shows that the Speed Control system is on. ...
Fuel Requirements
Your vehicle is designed to meet all emission regulations and provide satisfactory
fuel economy and performance when using high-quality unleaded gasoline having an
octane range of 87 to 91. The ...