Trip Accuracy

[Dryce]

How accurate are MB trip computers in reporting fuel consumption
and range?

I'm reckoning it's over optimistic by about 10% on consumption
on my W211 but I haven't had enough time to do any decent
averaging as yet. (The only other car I've had with an mpg
readout was a Honda and that usually was about 5% over
optimistic depending on journey type and sometimes a little
bit pessimistic in extended stop/start urban driving).

 

[R2D2]

My car reckons that when I've actually done 28/29 mpg it reports 26mpg

 

[GrahamC230K]

Not very then!

 

[Hutton1969]

The range in my CLK can go from 50 miles to 15 miles after just 10 miles of steady driving. I do not rely on it!

 

[DieselE]

My trip computer is about 5% pessimistic on fuel consumption. Being a diesel, there is no way I will test the range forecast to destruction.

 

[Dieselman]

My trip computer is about 5% pessimistic on fuel consumption. Being a diesel, there is no way I will test the range forecast to destruction.

Why would you need to do that, just work out the mpg properly by filling the tank brim to brim than check the mileage against the computer. When the computer says there is xx left in the tank refill and check it.

 

[DieselE]

Why would you need to do that, just work out the mpg properly by filling the tank brim to brim than check the mileage against the computer. When the computer says there is xx left in the tank refill and check it.

The range testing remark was intended to be a "tongue in cheek" comment. Another one bites the dust.

What I normally do is fill the tank to the brim and reset the trip mileometer. After 600 miles I repeat the process. That's the joy of a diesel and an 80 litre tank. It's only out of interest that I compare the actual mpg with that shown on the trip computer.

 

[Satch]

The "range" function annoys me.

It is more of an near instant range forecast based upon fuel flow at the time. So on a long steady haul it is OK but in slower or variable traffic quickly becomes a nonsense.

All other cars I have had update their range forecasts over a rather longer period and thus give a more realistic and reliable result.

Every time I fill up the range resets to 766 miles. That then plummets to around 450 within 10 minutes!

 

[R2D2]

Yeah but what a 10 minutes