canadian:

390km/72liters is pretty low. i would say you have a leak somewhere in the system, i.e., the fueltank, fuel lines or near the fuel filter. leaks in fuel line are more pronounced when fuel pump is working, i.e., line is under pressure. i remember a leak i had on the short rubber hose input to the fuelfilter of my previous volvo, a 740gle, which was visible only when the engine was running.

not to alarm you here but you need to you rule out if you have a leak before you drive that car anymore.

yt850
1994/855/5spd/na