I do the same journey most days , 100 miles round trip with 80% being motorway miles

I use the adaptive cruise set at no more than 70 but as it's always rush hour I'm usually cruising at 50 mph

The average for each journey on the trip computer has been 40-41mpg.

Is this accurate? If so I'm very impressed as my D4 only gave me 25 ish MPG.

Mine is a 4.4 TDV8 CURRENT : FFRR 2012 4.4 TDV8
GONE : Discovery 4
GONE : BMW M5
GONE : L322 Range Rover
GONE : 2007 MITSUBISHI OUTLANDER
GONE : SAAB 9-3 VECTOR SPORT
GONE : BMW M3
GONE : SIERRA COSWORTH
GONE : LOTUS CORTINA
GONE : MK1 MEXICO
GONE : MK2 RS2000

I think they are always a bit optimistic, mine says around 18 but I get closer to 15...

Does sound good though.... Pete

__________________________________________________
2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Parchment over Navy Interior. Sold
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand, Jet Interior. Sold
2002 L322 Vogue 4.4 V8 Epson Green, Ivory over Aspen Interior (Fatty Offroader) Sold
-Click for Project Fatty off roader-

I meant your MPG sounds good... not my 4.4V8 petrol... but it does sound good BTW....  Pete

__________________________________________________
2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Parchment over Navy Interior. Sold
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand, Jet Interior. Sold
2002 L322 Vogue 4.4 V8 Epson Green, Ivory over Aspen Interior (Fatty Offroader) Sold
-Click for Project Fatty off roader-

Haylands

My 3.6 TDV8 gives me an average of 19 so I'd say it's bloomin good
Either way, if you take optimism into account it's still better than your Disco

If you are cruising at 50 it could be your optimum mpg,sounds good figures to me.To actually put a spanner in the works ,most speedos are inaccurate unless they are calibrated meaning the mileage is not right and neither will the mpg.If you want to be accuratel log exactly what you put in at the pump in litres[on your receipt] you can then measure what distance you do un a map but probably unfeasible.You could check your distance covered on a measured mile that you can calculate the distance difference then giving an accurate Mpg!!!

I think I'll stick with the feelgood factor of 40mpg! CURRENT : FFRR 2012 4.4 TDV8
GONE : Discovery 4
GONE : BMW M5
GONE : L322 Range Rover
GONE : 2007 MITSUBISHI OUTLANDER
GONE : SAAB 9-3 VECTOR SPORT
GONE : BMW M3
GONE : SIERRA COSWORTH
GONE : LOTUS CORTINA
GONE : MK1 MEXICO
GONE : MK2 RS2000

it all depends how accurate your speedo is, and that can be affected by worn tyres vs. new ones.

The actual amount of fuel consumed by the engine should be fairly accurate, but it depends the speedo for the mileage part. You can of course use a GPS to measure your distance and fill the tank up, drive a bit then fill the tank again and work it out manually, but even filling the tank like that is hardly an exact science. And if you have a fuel burning heater that'll use some too in winter.

I reckon the computer is as near as accurate as you'll need it to be.

mine over reads by 10% (3.6) Cheers

James

Mine is consistently over-optimistic by 3mpg measured against computer reading vs tank fill/odometer method.

Real time mpg for mainly motorway miles at 70-75mph on cruise control over the past 7000 miles has been 27mpg which is reasonable for a 3 tonne 300+bhp bus!

getting 14mpg currently on my 4.4V8 gasoline 2014 FF Autobiography 5.0 SC
2008 FFRR (sold)
2008 BMW M5

Bear in mind though that filling the tank and using the odometer, doesn't take into account idling, sitting a traffic lights etc. The computer stops recording fuel consumption when the vehicle stops moving. So it will always be slightly higher than the filling the tank method.

Zirconblue wrote:

Bear in mind though that filling the tank and using the odometer, doesn't take into account idling, sitting a traffic lights etc. The computer stops recording fuel consumption when the vehicle stops moving. So it will always be slightly higher than the filling the tank method.

I just started playing with the consumption computer. I was able to see it hit 20.8 MPG(US). All I need to maintain that is a slight grade downhill at 35 MPH. 4 mile trip average was 17.6. I'm optimistic I'll hit 24mpg highway. I also play the lottery.

I Find the indicated mpg useful as a diagnostic tool rather than an accurate measure of fuel consumption, for example when the caliper was sticking on my last car the average mpg got worse which prompted the investigation and discovery of a very hot wheel.
FWIW I use the distance to empty more, a full tank is generally about 420 miles and one or two weeks later it's zero, meaning a trip to the filling station is required. Geoff

sako243 wrote:

Zirconblue wrote:

Bear in mind though that filling the tank and using the odometer, doesn't take into account idling, sitting a traffic lights etc. The computer stops recording fuel consumption when the vehicle stops moving. So it will always be slightly higher than the filling the tank method.

What is your source for that comment? Just curious since I have never come across anything like that. In fact when I was up in the mountains at my grandparents in the Highlands the on board was dropping whilst we were stationary watching a lek going on...