RangeRovers.net Forum banner

1 - 6 of 6 Posts

·
Registered
Joined
·
34 Posts
Discussion Starter #1
I have been using the MPG readout severl times a year on my 1998 RR 4.0 I teated it yesterday doing a steady 50 mph on a straightaway. At 108,331 miles on the speedo. the engine does not burn any oil.
I get 22.9 MPG. At 55 mpg I get 20 mpg and at 60 mph I get 19 mpg on the readout.
How much of that do you think is true
 

·
Administrator
Joined
·
27,820 Posts
You are expecting way too much from half a calculator... MPG is only an average since your last trip computer reset.
 

·
Premium Member
Joined
·
1,345 Posts
The mpg dash readout is calculated from the theoretical volume of fuel corresponding to the opening times of the injectors as controlled by the ECU. A lot of variables, some of which can vary with age/mileage. Like fuel pump pressure, resistance in the fuel filter, injector response etc. Then there is the distance traveled, which depends on the actual rolling circumference of the tires fitted.
Do it's just an estimate. If you want to really know your mpg, you'll have to calculate it yourself dividing the miles traveled between fuel stops by the volume of fuel.

Filip
 

·
Registered
Joined
·
566 Posts
if you want to remain happy just accept the numbers on the dash. If you calculate it properly based on actual distance & fuel used, you will only get upset.
 

·
Registered
Joined
·
62 Posts
Hi all,
i have found the the mileage function surprisingly accurate on my small stable of older British cars including Rover 3500 VDP, Jaguar X300, Jaguar XK8 and of course the 4.6HSE. The RR HSE computer provides far less information than the other cars, even the old Vanden Plas that is far older (85) (instantaneous consumption) which is surprising as obviously the engine management computer has the information.
As it is calculated on injector opening time it must obviously rely on injector condition and cleanliness for accuracy.
I do find that the range is often underestimated with the display indicating 'Less Than 80km Range' with upto 20 lt of fuel remaining although I have never run it out to prove the point.
out of interest, based in the country my RR gets between 13.8 and 16 lt/100 km although towing or difficult driving and towing can soon push it above 20.
regards
Al
 
1 - 6 of 6 Posts
Top