A clean MAP sensor only gets you smoother throttle progression on initial application and I doubt it will help steady load economy unless there is a leak. If you have larger than stock tyres the setting to fix speedo error is CCF - Instrument pack- MSP-ISP ( last on list) lowering the value increases the speedo readout. On my 255/55 R20 a value of 29 gives about 3.5mph over the GPS speed which I think is stock. Also look at the eco setting which is +7% and some D4 forum posts I’ve seen say setting this at -5% gives a truer mpg display. Other settings for rolling radius ABS, tyre size and rolling circumference ‘may’ ( esp the last one) be used by the auto box. Larger tyres mean higher effective final drive so if the car doesn’t know it’s higher it may think it’s towing something or going up hill and may hold gears longer and higher? 2012 TDV8 Vogue (L322)

So I don’t believe I have a leak as I cannot see any signs of misting, and there are no warning. But I will have a better look in the coming weeks.

I had to pop out so filled up and brimmed the tank. I reset everything and did a 15 mile round drip at mostly 30 and 50 mph. Trip computer said an average speed of 35mph and 24.5 mpg… I would expect higher than that.

Let’s see what my actual mpg is like after a few miles are driven this week.

I’ve also fiddled with the ccf settings to ensure those settings are correct (or the highest I can set for rolling circumference) and will compare to a gps figure… and real world figures when calculated.

Cheers for the advice so far  Currently driving: 2012 L322 SE Overfinch 4.4 tdv8

Past rides:
2014 Audi Q7 3.0d (good riddance)
2010 L322 Autobiography 5.0 Supercharged
2011 L320 HSE 3.0 sdv6
2014 Jaguar XF-RS 5.0 supercharged
2007 BMW 535D
2005 Mini Cooper S

https://www.fullfatrr.com/forum/topic59478.html

JayGee wrote:

What’s your miles remaining on the trip after a fill?

460 is quite low. Least I’ve had is 550 and most 630. What tyres are you on ? 2012 TDV8 Vogue (L322)

I’m on 285/45 R22 which is 3.5% larger than stock.

Click image to enlarge

Btw, appreciate the help and suggestions!  Currently driving: 2012 L322 SE Overfinch 4.4 tdv8

Past rides:
2014 Audi Q7 3.0d (good riddance)
2010 L322 Autobiography 5.0 Supercharged
2011 L320 HSE 3.0 sdv6
2014 Jaguar XF-RS 5.0 supercharged
2007 BMW 535D
2005 Mini Cooper S

https://www.fullfatrr.com/forum/topic59478.html

285/45 R22 are 7% over stock (255/55 R19 / 255/50 R20) on the L322. Could be pushing it for optimal gearing vs engine torque curve. 2012 TDV8 Vogue (L322)

Ah, yes the size I compared against was incorrect… I am indeed 7% larger than stock!
Let’s see how things look when I do the actual mpg calculation.

What do you mean by optimum gearing vs engine torque? Are you suggesting it could be less economical, or that there may be problems with this size increase?

I do plan to replace these tyres with a decent brand when they’ve been worn down. I’d aim to swap all 4 at the same time (I chose these due to poor timing financially) so can move to 285/40R22 tyres if necessary… but I chose the 45s due to the extra inch of tyre wall over 35s Currently driving: 2012 L322 SE Overfinch 4.4 tdv8

Past rides:
2014 Audi Q7 3.0d (good riddance)
2010 L322 Autobiography 5.0 Supercharged
2011 L320 HSE 3.0 sdv6
2014 Jaguar XF-RS 5.0 supercharged
2007 BMW 535D
2005 Mini Cooper S

https://www.fullfatrr.com/forum/topic59478.html

Engine will be turning lower revs per road speed and engine may not be at max efficiency and or as said earlier the gearbox is interpreting the higher effective gearing / load as a hill or a tow and holding higher than optimal revs. Also wider profile tyres generally have more rolling resistance and if they are budget tyres this also means they are less than optimal in this parameter.
Not sure how 22” wheels + bigger tyres play with ABS, active suspension etc either. 2012 TDV8 Vogue (L322)

So its been a few months since i last updated this thread and thought I’d revive it.

In this time i have replaced both rear callipers to ensure they weren’t dragging. Ive removed and cleaned my plenum, MAP sensor, and throttle body. Ive also had a partial gearbox oil change, along with fresh diff and transfer box oils.

I’ve not really seen any worthwhile change in fuel consumption, but I did find that the plenum and/or MAP sensor clean has improved the throttle response! She is less eager to drop a gear and more often uses the low rev torque instead!

And to add today, I have swapped the intake hoses for new silicone ones (Blue… just because!) and gave her a good dose of EGR cleaner to help ensure she’s as clean as she can be without stripping the engine. (And again, i am seeing an improved throttle response after doing this!!! Plus, i swear she’s quieter too…)

After all that i performed a DPF regen courtesy of GAP’s latest (on request) version to reduce the calculated soot from 16 to <1g.

I’ve not had a chance to see what difference that all has made, but an initial quick drive is not showing much difference. I’ll not chalk this up as a failure yet as i need to do my usual journey for a comparison.

The only other things on the list is to swap the fuel filter (I was sent an incorrect one) and possibly something with the high pressure fuel pump that has started making a new noise.

I’d also like to swap the tyres for a decent quiet tyre (i.e. verde all seasons) which may also be causing poor mpg due to their drag - they are bloody noisy!!! But that’s not going to be any time soon…

Any other thoughts? Anything i have missed that i should consider? Currently driving: 2012 L322 SE Overfinch 4.4 tdv8

Past rides:
2014 Audi Q7 3.0d (good riddance)
2010 L322 Autobiography 5.0 Supercharged
2011 L320 HSE 3.0 sdv6
2014 Jaguar XF-RS 5.0 supercharged
2007 BMW 535D
2005 Mini Cooper S

https://www.fullfatrr.com/forum/topic59478.html

So after a 240 mile round trip with mostly motorway driving with cruise control set to 75, I averaged 26mpg.

She is not running the mpg I expect when compared to others.

I’ve had my egr disabled and blanked which hasnt helped the mpg in any way (I do have better throttle response), and my soot level is around 9 and no indications of frequent regens.

The last planned change is the fuel filter, which is still to be delivered (the replacement arrived but was damaged in transit). I don’t expect the fuel filter to improve the mpg however.

What else can I check? Currently driving: 2012 L322 SE Overfinch 4.4 tdv8

Past rides:
2014 Audi Q7 3.0d (good riddance)
2010 L322 Autobiography 5.0 Supercharged
2011 L320 HSE 3.0 sdv6
2014 Jaguar XF-RS 5.0 supercharged
2007 BMW 535D
2005 Mini Cooper S

https://www.fullfatrr.com/forum/topic59478.html

Was this mpg worked out from fill to the brim vs actual miles or the trip display. If your tyres are bigger than stock both your miles traveled and trip mpg will be under displaying. Over 75mph the mpg drops to sub 30mpg on mine and you also have cheap tyres which will likely have extra rolling resistance so 26mpg is not that far off what I’d expect.
Also with that wheel diameter if the speedo is saying 75 your actual speed will be closer to 77mph 2012 TDV8 Vogue (L322)

Thanks JayGee
So far my MPG usage and concerns have been down two avenues.
1) Actual MPG. This had been parked due to time to get enough to get a true average. This morning i updated my tracking spreadsheet i started in Feb… more on that in a bit.
2) in car calculated MPG. This one i am concentrating on more as it gives me the journey by journey comparison.

The reason why i am using the in car MPG despite it potentially being inaccurate is that it is at least consistent. The car thinks it’s driven, say, 100 miles and will base its calculations on that. If it develop a fault (such as split pipe) causing my MPG to plummet, the in car MPG will reflect this. With that in mind it is still a useful figure to use.

I can drive a 10 mile stretch of road, fix something on the car, and then drive that same stretch of road. Those MPG comparisons can then be made.

To pick up on your points in your last post and previously…
Yes the tyre sizes will make a difference. They are bigger so my speedo and in car MPG will be less accurate as the miles the car thinks its driven vs what it has actually driven will differ.
Your MPG drops to 30 when driving at 75mph. That is good to know, and nearer to my 26mpg i was getting at that speed. That’s in the realms of my tyre drag…
Cheep Tyres. This is one area that i think is having the biggest negative effect, and may be the cause of my MPG differences before and after their fitting.

If the new tyres were identical in every way except their sizes (i.e. the same drag) then i expect my calculated MPG would be roughly the same, but actual MPG would differ. (Putting rotational mass change to one side for now)
However, because I have bought cheap tyres (due to bad timing - it was not long before Christmas when I HAD to purchase them) and they are NOISY… i expect their drag is far greater than before.

Now, back to the actual MPG of my car…
I typically get between 22 and 25 in car MPG depending when I reset and where I drive. My calculated mpg for the last 6 fill ups is between 19.5 and 21 MPG
Over on the DPF thread i posted on, Range Rover L322 posted that he also gets similar actual MPG. I also remember another member posting their actual MPG and IIRC that was similar also?

So the reports of the first V8 RR getting over 40MPG, and other members stating their car shows 30+MPG… does that mean they are also actually getting low 20’s if they do the maths themselves?

Now, while I may have delved into this rebut hole with the MPG… I am happy that I have improved the drivability of my car by cleaning the MAP, and MAF sensors, plus by spraying EGR and intake cleaner into the intake. Its small, but very noticeable throttle response improvement.
Many would say “snake oil” and would agree they are limited in what they can actually do while being burned off… but even if they only do a tiny bit of a clean, that tiny bit has improved my throttle response.[/list] Currently driving: 2012 L322 SE Overfinch 4.4 tdv8

Past rides:
2014 Audi Q7 3.0d (good riddance)
2010 L322 Autobiography 5.0 Supercharged
2011 L320 HSE 3.0 sdv6
2014 Jaguar XF-RS 5.0 supercharged
2007 BMW 535D
2005 Mini Cooper S

https://www.fullfatrr.com/forum/topic59478.html

I am planning on swapping the tyres on my car… at some point.
I want to go for a decent tyre, and was planning to swap two at a time to help spread the cost, however i am now looking to swap all 4 so need to save the pennies!

I am running 285/45 R22’s at the moment, but plan to drop to 275/40 R22’s so will need to do all 4 at the same time.
The reasons for this are:
1) They are slightly narrower tyres so will effectively have 40cm less tyre width in contact with the road in total. That has to help with some of the drag! Most Eco cars (looking at you EVs!) have skinny tyres for this very reason…
2) they look better. I parked up next to an L405 with 22’s and they just looked better. Mine look good and will fit the wheel arch nicely, but in comparison they look almost too fat.
3) my speedo will be out less… not really a reason to change (I just need to change the CCF settings) but worth noting!

Yes I’ll loose a bit in tyre wall depth… but i am expecting a decent tyre to behave better than the crap i am running on at the moment. Currently driving: 2012 L322 SE Overfinch 4.4 tdv8

Past rides:
2014 Audi Q7 3.0d (good riddance)
2010 L322 Autobiography 5.0 Supercharged
2011 L320 HSE 3.0 sdv6
2014 Jaguar XF-RS 5.0 supercharged
2007 BMW 535D
2005 Mini Cooper S

https://www.fullfatrr.com/forum/topic59478.html

Ffrr-lover wrote:

Over on the DPF thread i posted on, Range Rover L322 posted that he also gets similar actual MPG. I also remember another member posting their actual MPG and IIRC that was similar also?[/list]

That other person was Range Rover L322…

As requested, these are my calculated results. One fill up was missed… but still gives an indication of what my car is running at.

 Currently driving: 2012 L322 SE Overfinch 4.4 tdv8

Past rides:
2014 Audi Q7 3.0d (good riddance)
2010 L322 Autobiography 5.0 Supercharged
2011 L320 HSE 3.0 sdv6
2014 Jaguar XF-RS 5.0 supercharged
2007 BMW 535D
2005 Mini Cooper S

https://www.fullfatrr.com/forum/topic59478.html