Fuel Comsumption/Efficiency - W203 -C180

[fixfox]

I tried to benchmark my engines performance today. I started by driving till the engine was adequately warm (90º C) then went on the highway.

While driving at a constant speed of 110km/h, I pushed the reset button to begin measuring the fuel consumption (at that speed).

I expected to see it read 6.8 l/100km as listed for this engine type (W203, yr 2002) Highway: (6.8 L/100Km) [42 mpg uk]

To my surprise, it leveled out at 7.4 l/100 km after 2 minutes and stayed there throughout (i.e 10 minutes). I took my foot off the accelerator as i approached the end of the highway and it then dropped to 6.9 l /100km.

Does this mean my engines fuel comsumption has gone up?
Is 6.8l/100km really achievable for this engine while driving normally on a highway(at constant speed)?

The tank was filled with Shell V-Power 95 octane.

 

[nickcc101]

If your W203 is the 2 litre non turbo like mine then you can expect the max MPG to be about 32. I get about 18 mpg around town and 32 on motorways.

 

[wemorgan]

A few things that would change your efficiency:

tyre pressure
air temperature
car electronics (air-con etc)
windows open/closed
no. of occupants + luggage
road gradient

Though I would be pleasantly surprised if your car could achieve 42mpg at 110kph, maybe at 100kph though.

 

[daveuj]

Hi Fixfox I have a c180k coupe and got 40 MPG Shell V Power on a trip to Heathrow 138 miles had 4 adults and 3 cases in the car.
But only got 38 MPG on the way back (went to some towns).
You will never get the same figures as you cannot recreate the same conditions used to perform comsumption tests.(No wind,test track,car in the best tune,tyre pressures and time to get the best results.)

 

[fixfox]

If your W203 is the 2 litre non turbo like mine then you can expect the max MPG to be about 32. I get about 18 mpg around town and 32 on motorways.

Yes, it's a 2.0L non-turbo..... and the 7.4 1/100km converts to 31.7 mpg (US) which is close to your 32mpg

 

[fixfox]

A few things that would change your efficiency: [/QOUTE]

tyre pressure : standard (per fuel flap spec)
air temperature (20º C)
car electronics (air-con etc) : aircon off --- music (CD) on
windows open/closed : closed
no. of occupants + luggage : 1 (driver )
road gradient : relatively flat .... with slight uphill and downhill slopes

Though I would be pleasantly surprised if your car could achieve 42mpg at 110kph, maybe at 100kph though.

units convertion here and what I got was 7.4 l/100km which is equivalent to....38 mpg (imp) and 31.8mpg (US)

 

[fixfox]

Hi Fixfox I have a c180k coupe and got 40 MPG Shell V Power on a trip to Heathrow 138 miles had 4 adults and 3 cases in the car.
But only got 38 MPG on the way back (went to some towns).
You will never get the same figures as you cannot recreate the same conditions used to perform comsumption tests.(No wind,test track,car in the best tune,tyre pressures and time to get the best results.)

Your's is a kompressor so obviously much better on fuel.