Your car seem to show only 6km/l.....

Do you reset the FC reading when on the highway cruising?

That does not show the true consumption.

Alvin,

Your average speed cannot be 100km/h. do you mean, Max speed?

Average speed of 100km/h means you travel around 140km-160km/h on the highway to make up for the 30-40km/h in town.

What would be accurate to calculate is to:
- pour tank full of petrol (first click)
- reset trip A
- When refuel, note amount of fuel use
- check trip A
- Take trip A mileage divided by fuel used
Repeat and average accordingly

I dont believe the Civic can do 17-18km/l mix driving (with an average speed of 100km/h).

I have owned quite a few cars from Japanese to Malaysian to Germans to Koreans. (mixed with tracking and calculations of family cars)

I know what kind of fuel consumption for a specific type of car.

Thats why I know if one is trying to pull a fast one.

No. But my sister is. She is getting 12-13km/l city and highway driving (20/80)

CT200h

Petrol used: Shell 95
Engine Oil: Shell Helix Ultra 5w40
Pure highway driving: 19km/l (around 760km per tank)
Mixed driving: 18km/l (90% town, 10% highway)
Mileage: 100,000km
Driving mode: medium footed

GLC250

Petrol used: Shell 95
Engine Oil: Petronas 5w30
Pure highway driving: 10km/l
Mixed driving: 6km/l (90% town, 10% highway)
Mileage: 50,000km
Driving mode: medium footed

Lexus NX

Petrol used: Shell 95
Engine Oil: Shell Helix Ultra
Pure highway driving: 12km/l
Mixed driving: 8km/l (90% town, 10% highway)
Mileage: 100,000km
Driving mode: medium footed