Hi, I'm new to a 2017 L405 3.0 TDV6 (previously Disco4) and am amazed at the inaccuracy of the fuel consumption display and also the indicated miles to oil and DEF service. So I'd be interested in hearing some expert views.

First, after over 1,000 miles of careful driving (Eco readout 98% to 100%) the average MPG displayed is 35.8, which I would be pleased with, but doing exact brim-to-brim refuelling measurements the calculated real consumption is only 30.7 MPG - and that assumes the milometer is giving true mileage covered and not also exaggerating! That's a significant amount of lying.

Secondly, the displayed distance to next oil service is tumbling at over twice the rate of miles actually covered, which will mean next oil service will be at roughly 7,000 miles since last service and not the 16,000 miles quoted.

Finally, the displayed distance to DEF service is erratic ... sometimes tumbling slower than actual miles covered, but more often tumbling much quicker.

My journeys have been mixed commuting of 10 miles each way and longer runs of up to 100 miles if that makes a difference.

Thanks

the short journeys will be bringing it down. There is a long running thread of dpf regeneration on here. If i understand it correctly, it’ll try regeneration on a short journey but not complete as the journey isn’t long enough and each regen process dilutes the oil, and if its not completing, then its trying again and diluting the oil more often … which in turn reduces the mileage before service quicker too. V8 or else ...

It's an indicator, not an absolute measurement, the same way that (for example) auto high beam is a driving aid, not a replacement for driver control.
It's impossible for a fairly simplistic measurement to take account of all factors affecting fuel usage economy - on any vehicle, but it will be consistent within its own parameters.
To be honest, if you're looking for fuel economy, then you have the wrong vehicle. It excels at many things, they come at a cost, part of which is fuel usage.

If you want to calculate it yourself, then you need fuel quantity, fuel age (Cetane rating) ambient temperature, journey length, distance, oil & exhaust temperature, time and distance spent in each gear, throttle demand limits and rate of rise, tyre pressures, vehicle load, wind speed and direction, aircon load, electrical load, roof loading, vehicle mass and a few other minor factors to get an accurate measure.
Or you could just do the traditional 'blue feint ruled A6 notebook' in the drivers door pocket with date, fill quantity and mileage and average it out over some arbitrary time period.

@fatdivot:

Read this thread in full:

https://www.fullfatrr.com/forum/topic60839.html

For my FFRR TDV6 mostly short 8 mile to 16 mile journeys, 1 real mile = 3.83 Service Miles, so 16,000 = 4177 miles between services.

Welcome to the real World!  “If it ain’t broke, don’t fix it” -where’s the fun in that?

Get a Vgate iCar Pro and App for your phone.
Get an iCarSoft LR V3 diagnostic tool so you can force regens if needed.
You will then have a much better idea of what is going on with your DPF, and be able to act accordingly.  “If it ain’t broke, don’t fix it” -where’s the fun in that?

Get the "Road Trip Lite " app which gives you the true mpg figure. It's always about 5mpg difference to the car's display.

I am always amazed at the figures posted on here about consumption. All LR cars from 1984
2021.5 Vogue SE D300 Carpathian Grey
2018 Vogue SE British Racing Green GONE

lol as I posted here recently mine was serviced about a year ago with 24k miles it's now done just under 27k and it's saying service is required. It dropped down this low simply by moving it in and out of the garage for the last 3 months. overfinch modified

Chalky wrote:

Get the "Road Trip Lite " app which gives you the true mpg figure. It's always about 5mpg difference to the car's display.

I am always amazed at the figures posted on here about consumption.

Dont forget your mpg will go out of the window depending on how many times the DPF regenerates per fuel tank fill, as you use fuel to do a AR plus all the factors Phoenix mentions.
FBH also takes the juice.

If due to journey length you have a failed Active Regen, then it will look to do another AR the next journey when conditions are met. More juice

Short slow journeys increase the soot load quicker = sooner/more AR, compared to Motorway driving where Passive Regen can occur to reduce soot load.

I change the oil every 3k miles and its the service countdown that informs me to do it. 2018 SE SDV8 4.4 Byron Blue

#2 what Kot said (as one of our resident experts on this subject)

I expect Luxmoggy will be along to chip in his 2p soon……

Yes, the dashboard readings are sadly fantasy, to be polite. “If it ain’t broke, don’t fix it” -where’s the fun in that?

so this mpg was really 15mpg....









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No Stan, it was about 33-35 mpg. All LR cars from 1984
2021.5 Vogue SE D300 Carpathian Grey
2018 Vogue SE British Racing Green GONE

@Stan:

Not quite that bad hopefully, I’ve been keeping a careful log of litres purchased vs miles driven, mostly short urban journeys (often around 8 miles), and my consumption varies from 20-29mpg depending on traffic and weather, -if its freezing, I use the remote start which wastes fuel.

I’ve not done the “single-trip brim the tank and drive economically” thing, because it doesn’t prove much in the real world, but I expect I’d get much better on a run across country, but maybe not so much on the motorway.

What does my display say? Dunno, I never look!  “If it ain’t broke, don’t fix it” -where’s the fun in that?

According to Road Trip Lite my car is averaging 29.61mpg and that is nearly all under 10 mile trips!

Why buy a FFRR you ask if that's all you do? I drive a lot off road and some long trips when I get about 35mpg (41 according to the car!!) All LR cars from 1984
2021.5 Vogue SE D300 Carpathian Grey
2018 Vogue SE British Racing Green GONE

[quote="Chalky"]Why buy a FFRR you ask if that's all you do?/quote]

Simples: to waft about the land in luxury and imperiousness, looking down on all you survey, type of thing......

 “If it ain’t broke, don’t fix it” -where’s the fun in that?