Jeep 2008 Commander - Manual (Page 338)

CAUTION!
Only vehicles with the E-85 fuel filler cap (gas cap)
can operate on E-85.
ETHANOL FUEL (E-85)
E-85 is a mixture of approximately 85% fuel ethanol and
15% unleaded gasoline.
E-85 Fuel Cap E-85 Badge
338 STARTING AND OPERATING