I am sorry if I hijacked this thread, I think it started asking what was "normal" MPG - it seems that normal is in the eye of the beholder. I would not want to argue with QinteQ but I dont think MPG is linear at all. And, cruise control is a liability on hills! I get better mileage at 60 than I do at 70 but not as good mileage at 40 which seems to be the slowest I can drive without the transmission changing down. That indicates a fuel consumption curve. However, my main concern is the difference I find between the happy numbers displayed on the Trip Computer and the stark reality revealed in the old fashioned calculation at the pump. Clearly the ECU must have erroneous information floating around to come up with figures that are such a long way off? If so, what othere errors are being made as a result? And, for that matter, where is it coming from? There is no fuel flow sensor as such. I wonder if the ECU can be remapped to take out the EGR valve?

Lastly, really poor mileage is likely as not a dirty Air Mass Sensor (providing incorrect voltage to ECU) if it is bad enough to trigger a fault warning it is likely to show up as one of several EGR faults, even though it is nothing to do with EGR, or as in my case; poor condition injectors - right?

vrc8883

 

Are u reading in mpg or km/l?
Bearing in mind the trip computer is us gal, ie 40mpg equal to 33mpg

 

tavelmad, that is an interesting thought, although I have been told that the car sold in the UK features Imperial Gallons by several dealers just because I was uncertain if it was displaying US or Imperial Gallons. My wife has the car today so I cant check the manual. Also, my Trip computer average MPG was 44.7 on my recent lengthy trip and my calculated average about 34.27 which should be 37.22 (if 44.7 is USG) so it would still be out by 3MPG on average or an errror of 10%

 

your probably right, just the settings let you choose "metric" or "us"
In fact I was wrong about the conversion anyway
40mpg (us) would convert to 48mpg (uk)

 

- good quality fuel cheepo fuel
- badly calibrated pumps delivering short
- controlling the measuring techniques of both gallons and miles
- tyre pressures
- UK / US gallons
- style of driving / right boot
- gearbox software / cruise
- winter fuel density (+) / summer fuel density (-)
- air temp / elevation
- tank to tank, no traffic lights or stops
- etc


Making a meglo attempt at control of the situation to arrive at an accurate MPG might well end with both, the (1) scientific and the (2) bog standard car's odometer being equally 2% out. In the case of this thread if a 2.8 CRD returns 32MPG mixed I see no point in spending on 'extra' work to improve MPG. The only reason in my view is if your vehicle give consistently less than 32MPG mixed ~and~ its definitely not down to driver error ~and~ your annual mileage is megga high at 30+ thousand or 4 times the domestic average per annum.

When our American cousins complain that they are getting 20+US-MPG from their petrol [or diesel] they are actually getting 24+UK-MPG, or for example 35+US-MPG would be 42+UK-MPG, because of the 'size' of their gallon.

 

I'm getting only 26mpg out of our 2.8L 56 plate XS! Even though I've changed the Oil (Motul 5w-30 100% synth) and filter. New genuine air filter and fuel filter! Even used BG244 in the fuel with Shell V-Power (Only use V-Power) and Archoil 6200 products and Archoil AR9100 Advanced Friction Modifier & Oil Additive (250ml) | Lubricant Treatments and Additives in the oil!... So what am I missing here?

 

Totally agree

Regards
Richard

 

Oh... And only 83k on the clock!... Tyres (Goodyear all new) with 37psi. I'm unsure if anyone can get 33mpg out of the car round town...

 

Also used this stuff in it- AR6500 is a new and powerful blend of additives designed to safely clean the fuel system, combustion area and emission control system components such as the diesel particulate filter (DPF) and catalytic convertor

Archoil AR6200 Combustion Catalysts / Burn Rate Modifier and Lubricant

AR6500 is a new and powerful blend of additives designed to safely clean the fuel system, combustion area and emission control system components such as the diesel particulate filter (DPF) and catalytic convertor

 

HiTa Timmy, I don't think anyone in the history of man has ever claimed to get 33MPG from a 2.8CRD 'around town' I'm not a gambling man but I'd bet my house on the fact that no one will ever [real world] achieve that - ever.

My claim, and most others I'm sure will agree that a mixed 30+MPG is possible, but that in turn depends on what mix. My point was that improving your own and the cars driving behaviour is the only effective way to achieve a 30+MPG mixed. The gentler driving style with a 'light-boot' will use less RPM will use less fuel - its really more a question of what I / me / now / can do, get into the habit of doing that 365 days a year and you are on a winner.

In town you can't really use cruise, other mixed driving you can and should use cruise, cruise [the puter] not only knows better than you but can change several thousand times a second and make adjustments. Try it .. .. do 30 or 40 or 50 MPH without cruise and the same speeds with cruise you will find you (1) do any speed with a 20+% reduction in given RPM for the same speed [reduced fuel volume cost] and your (2) gearbox changes up earlier more reduced fuel volume cost.

In additive / chip-MOD terms I've never had a lot of time for the alchemy it promises. I can see that blanking the EGR which needs a re-MAP [see #18 ] will help fuel across all RPM and lifestyle uses. In short there's nothing much that a 'school run only' style use of a 2.8CRD can do to improve MPG but we all knew that when we joined the Voyager army. There is however a lot we can do on mixed and above driving .. .. starting with the right foot.

Best of luck Timmy.