Lower speed to 6 klms

it has done 48,000 klms per year which indicates that it is not a suburban car ( averages 20,000 klm /year)
That indicates that it is a commercial / travelling representative car or government car
you would be well advised to have it check by an auto club inspector (RACQ, NRMA , RACV or the state where you are) and get a comprehensive report
google -- reports on holden cruze cars -- and read forums from users and owners

best at 10 liters per 100 klms , average around 12 liters /100 klms
fuel consumption depends largely on load , speed , operating conditions , towing, highway/city, off road so an exacting answer is not possible as it all depends on the operator and the driving skills

I believe you need. Calculator not a mechanic!

Toyota service schedule is 10.000 klms /miles or 6 months which ever comes first. If you want to keep it in good condition then change the oil and filter every 5.000 klm/ miles with a book service done on the 10.000 or 6 month interval

The normal idle speed for almost every car is about 7500 to 8000. I'm not sure if you would or not, but if you have performance parts on it them i would stick a little over 8000 but around 7500 is the best idle speed to have.

hit the monitor button on control panel. you will hear dial tone,than use the up/down arrows on top panel marked volume and raise or lower.

Work fast.

Your killing a fly with a sledge hammer. If you do a ALL JOB clear from test mode 6 instead of SHIPMENT SET... you wont loose all your one-touches or fax parameter settings.

Press
Function
72
set
1

touch yellow keyboard key like 01
enter fax number
set
enter name
set
stop

you can plug your pen drive backside. if its cant work your computer speed is slow.