MPG Calculations

[Gollom]

How exactly is this calculated (in my case, on a W208)? For instance if I do a 40 mile trip non-stop and it says 38mpg is that 38mpg over the whole trip or just the last x number of miles. What about if I stopped for a coffee half way for 15 mins? I'm sure you understand what I am asking!

 

[Dieselman]

It's an average over the journey. Iirc, it's 3 hours off time before the trip computer resets to a new journey.

 

[renault12ts]

When you stop, the trip computer stops also, but then resumes when you resume.

So if it takes you 2 hours to get to your destination with a 1 hour rest, the trip computer will show one hour travelled.

 

[MarriedBlonde]

It's an average over the journey. Iirc, it's 3 hours off time before the trip computer resets to a new journey.

I can't be 3 hours off time in the new cars as my from start readings carry on from where they left off in the morning when I cummute to work

 

[fah320]

I can't be 3 hours off time in the new cars as my from start readings carry on from where they left off in the morning when I cummute to work

As far as I know it is 5 or 6 hours...

 

[Brian WH]

As far as I know it is 5 or 6 hours...

Correct it is 5 hours before it resets on new MBs.

Consider the time as Driving time only. The mpg is over whole journey and is an average, at average speed as shown.

 

[Gollom]

Correct it is 5 hours before it resets on new MBs.

Consider the time as Driving time only. The mpg is over whole journey and is an average, at average speed as shown.

So if I drove for 7 hours non-stop the MPG would be average over the whole trip? What about if I stopped at hour 4:30 for 1 hour?

Really having a problem getting my head round this!

 

[Dieselman]

So if I drove for 7 hours non-stop the MPG would be average over the whole trip? What about if I stopped at hour 4:30 for 1 hour?

Really having a problem getting my head round this!

It just calculates against actual engine running time, not when switched off.

MPG wouldn't change anyway as it wouldn't be clocking any miles or using any fuel.

 

[Brian WH]

So if I drove for 7 hours non-stop the MPG would be average over the whole trip? What about if I stopped at hour 4:30 for 1 hour?

Really having a problem getting my head round this!

The clue is in the sentence "Driving time". Stopping for up to 5 hrs doesn't alter the average mpg.

If you stop for more than 5 hours it resets.

 

[oldcro]

On the new E class and probably other models the average consumption is reset if the engine is stopped for 4 or more hours, that's time for one stop not accumulated time over numerous stops

So forget the time unless stopped for 4 or more hours, it just divides the miles travelled by the amount of fuel used.

The remaining distance on the fuel available is calculated on the previous 20 miles average consumption rate.

 

[Mactech]

So if I drove for 7 hours non-stop the MPG would be average over the whole trip? What about if I stopped at hour 4:30 for 1 hour?

Really having a problem getting my head round this!

I find it easiest to look at the factors involved in the 'MPG' and 'MPH' tags.
There is no time factor in 'miles per gallon' so it is simply the distance you travel for the amount of fuel used. Time, (either traveling or stationary) dosn't factor at all.
MPH on the other hand, obviously has a time factor in it
But it dosen't matter how much fuel you use.....if you have the money to pay for it....