All gasoline sold in the United States is required to contain effective detergent additives. Use of additional detergents or other additives is not needed under normal conditions and would result in additional cost. Therefore you should not have to add anything to the fuel.
See also:
Passenger Seat Storage — If Equipped
Some models may be equipped with storage under the front passenger seat. Pull
outward on the latch to open the storage compartment.
Passenger Seat
Storage ...
Anchoring the load
A boot mat is provided (optional for Fiat Doblò Cargo base versions). To fasten
the load, fastening hooks are provided (quantity varying according to versions)
fig. 132 secured to the floor ...
Wind Buffeting
Wind buffeting can be described as the perception of pressure on the ears or
a helicopter-type sound in the ears. Your vehicle may exhibit wind buffeting with
the windows down, or the sunroof (if ...