Model : S Class (3.0)
Transmission : Auto
Petrol used : Random
Fuel Consumption : RM170 @ 500km +- 30km / RM0.34 @ RM1.96
Driving Condition : City 40% Highway 60% @ Gentle Acceleration
Average speed : City 70kmh Highway 120kmh @ Occasionally >200kmh
A/c usage : 90% Sunroof @ Morning
Modification : Stock

To chunk in some data:

Manufacturer: Mercedes
Model: W204
Variance: C200 Kompressor
Engine: 1800cc 4 Cylinder 186 bhp
Full Tank: RM 120 ≈ 65L @ RM1.85/L

(Readings from on-board meter)

City + Horrible,Terrible, Vegetable Traffic :
Travel at 100km @ 4 hours drive per day
Heavy footed
Average 10.9L/100km
Approximately 550km for each full tank (Close to empty)

Highway :
Middle footed
130kmh
Average 6.6L/100km
Approximately close to 750-800km

Lowest I've ever recorded was about 6.4L/100km @ 90kmh constant.
According to the meter, the remaining travel millage with full tank is 980km (Which the on-board computer estimated, excluding reserve tank). But not able to maintain at the speed for more than 2 hours. It's either I will fall asleep or toll/traffic.

Just my 1 cent share.