Fuel Consumption test

[The Pan Man]

I posted last week that I would do this random test over my next trip and here are the results.
Trip 1 156 miles 40miles A & B Roads 116 M Way miles Trip MPG 47.1 Av Speed 55 MPH
No Stops
Trip 2 18 Local B roads 1 Stop half way Trip MPG 35 Av speed 28
Trip 3 182 Miles 81 Miles A & B Roads 3 Stops Trip MPG 46 Av Speed 46
Now I have always said that my average MPG is 39 - 41 MPG
So how does the computer fair with a brim to brim same pump test. Preyy damm good is the answer. Calculated from above 41.23 MPG and from the computer 40.9 MPG.
I know this is not a crucial / critical monitored test but you cant argue with the results, this was my normal driving not keeping off the gas for the sake of proving a point.

 

[wemorgan]

Thanks for the information. Roughly what speed were your cruising whilst on the motorway?

 

[kth286]

for people that have not followed previous thread, be useful to know the car.

 

[wemorgan]

It's a 2003 E270 CDi

 

[survey]

I certainly wish my computer was as accurate. Mine reads between 2.5-7% optimistic! Apparently there is no way to adjust the calibration of the on-board computer - unless someone on this forum knows differently??!!

 

[The Pan Man]

Thanks for the information. Roughly what speed were your cruising whilst on the motorway?
__________________
Will

Do you expect me to answer that?

 

[wemorgan]

Thanks for the information. Roughly what speed were your cruising whilst on the motorway?
__________________
Will

Do you expect me to answer that?

"Trip 1 156 miles 40miles A & B Roads 116 M Way miles Trip MPG 47.1 Av Speed 55 MPH "

I thought with an average of 55mph and with 3/4 of your distance being on the motorway it would have been ~65mph. But if it was faster then to average 47mpg is better than I originally thought.

 

[The Pan Man]

WEMORGAN, You are basing that assumption on the wrong end of the speed range.
Average Speed = Distance / Time agreed?
So on the Motorway for 140 miles accelerate to 70 mph engage cruise in 2 hours leave motorway, agreed? So we leave the motorway and for the next 16 miles we do 16 MPH Journey time 3 Hours Therfore average speed is:: 156 / 3 = 52 MPH. Now my personal experience and I have a lot of it is that any journey of 2 - 3 hours with A, B & C class roads or towns and cities at either end will knock your average back in to the low 50's. If the journey is 6 Hours or more and almost all motorway you can get some good results, but for every minute you sit in traffic your average is dropping. Does that make sense? So as near as I can calculate to average 65 MPH my motorway speed would need to average 106 MPH, bit risky that.

 

[wemorgan]

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