MPG... What's the problem?

I've got a fuel economy query here too. Had my Evoque Dynamic (SD4 Auto, Pan Roof and Tailgate, no spare tyre) and could average 35mpg from Stockton to Newcastle when the weather was below freezing. I know the MPG debate is done to death and we won't achieve manufacturer's figures, but the same journey at 70mph is now giving below 30mpg in warmer temperatures (albeit 5C!). At 70mph, i'm pulling about 1800rpm in 6th gear, i'm sure this is higher than it was when i took delivery of the car. I got 40mpg at times when the car was new, not seen over 36 on a long steady flat level drive for a while! Any ideas what could be happening? Is the ECU in these cars a self learn unit? I'm tempted to reset it.

(04-04-2013 03:33pm)KaDargo Wrote:  I have worked out that if I fuelled up at a motorway service station, and drove at 70 mph or less till on the motorway network without stopping or jams till it ran out, I would average 40-45 all the way.

I've tried this on long French motorway journeys and my results has been that averaging 70 mph gives 34.5/35.5 mpg and averaging 80 mph gives 32.5/33.5 mpg.
Tim

My TD4 gets about 30-32mpg which s fine, but what grates on me is that LR quote such rediculous figures - something like just shy of 50mpg!!!!

It wouldn't have influenced my decision to buy but my word LR, stop the blatant lies!!

It isn't LR it's the Official Government test figures and the way they are calculated - pity all those Prius owners who thought they were saving the planet yet cannot even get 45mpg from their 75mpg cars......... Also those who have purchased the Vauxhall Ampera and find in cold weather that it runs all the time on it's tiny petrol engine and struggles to get 30mpg rather than the government figure of 300mpg!

Just listening to the R4 You and Yours consumer programme regarding misleading official test fuel consumption - the Advertising Standards Agency in the UK now requires all ads to carry a disclaimer that the Official test figures are achieved in lab/ test conditions and will not be achieved in day to day motoring conditions. The "Official" MPG figures are something required by the EU not the UK Government and it turns out that the EU hasn't yet been able to come up with a better way of doing the figures................

(07-04-2013 09:31am)XFullFatTim Wrote:  It isn't LR it's the Official Government test figures and the way they are calculated - pity all those Prius owners who thought they were saving the planet yet cannot even get 45mpg from their 75mpg cars......... Also those who have purchased the Vauxhall Ampera and find in cold weather that it runs all the time on it's tiny petrol engine and struggles to get 30mpg rather than the government figure of 300mpg!

I am amazed that so many people have still not got their head round this. - and that the motoring magazines of all people have been no better until vey recently (though some still talk of the official figures as if they are still achievable). Plus, how many people moan about the mpg they are getting while ignoring that the biggest cost for most is depreciation?

People shouldn't be moaning as the more they do the more likely it is that the government will rely on a more "realistic" set of figures while keeping the thresholds the same - hence increasing everyone's road fund licence (or whatever it's called)

I also changed my wheels (the same day I got my car) from 18" to Style 6 20" (With 255/45/20 tyres). A huge improvement on the looks and the cars handling felt great too.

As I had not driven more than 28 miles on the 18" I spent the next three months very frustrated with my Evoque's diesel consumption, averaging 21mpg local journeys and around 28mpg on the motorway (driving at speeds of 65 - 75 mph). On a full tank of diesel I could only get around 320 miles. I really was not happy about these very poor fuel consumption figures and after a few calls to the dealer and also Land Rover Customer Services, my car was booked in for a diagnostic session. I had a list of little items I asked them to resolve (these were all done) and they felt that The onboard computer needed to be told that the car now had 20" wheels not 18"'s. I had also changed my tyres to 245/45/20 Michelin (OEM rubber for the Evoque) even though I felt the 255/45/20 were closer in size to the 18" diameters.

The rub of it all is that I am now averaging 36mpg and 460 miles from a tank of diesel, so do you need to tell the onboard computer there is a wheel change??? Possibly.

(11-04-2013 12:44pm)RichWilkie Wrote:  I also changed my wheels (the same day I got my car) from 18" to Style 6 20" (With 255/45/20 tyres). A huge improvement on the looks and the cars handling felt great too.

As I had not driven more than 28 miles on the 18" I spent the next three months very frustrated with my Evoque's diesel consumption, averaging 21mpg local journeys and around 28mpg on the motorway (driving at speeds of 65 - 75 mph). On a full tank of diesel I could only get around 320 miles. I really was not happy about these very poor fuel consumption figures and after a few calls to the dealer and also Land Rover Customer Services, my car was booked in for a diagnostic session. I had a list of little items I asked them to resolve (these were all done) and they felt that The onboard computer needed to be told that the car now had 20" wheels not 18"'s. I had also changed my tyres to 245/45/20 Michelin (OEM rubber for the Evoque) even though I felt the 255/45/20 were closer in size to the 18" diameters.

The rub of it all is that I am now averaging 36mpg and 460 miles from a tank of diesel, so do you need to tell the onboard computer there is a wheel change??? Possibly.

Only if the rolling circumference changes. This would also affect your speedo reading

IIRC The rolling diameter of all versions of Evoque is the same regardless of the size of wheel - it all depends on the section/profile of the tyre. If LR didn't do this then damage to the IRD/VCU would occur due to transmission wind-up if you had to run on the space saver spare if you have one. It has long been the case with other LR products, the spacesaver spare is a different section/profile to the running wheels/tyres but the rolling diameter is the same.

(11-04-2013 03:44pm)XFullFatTim Wrote:  IIRC The rolling diameter of all versions of Evoque is the same regardless of the size of wheel - it all depends on the section/profile of the tyre. If LR didn't do this then damage to the IRD/VCU would occur due to transmission wind-up if you had to run on the space saver spare if you have one. It has long been the case with other LR products, the spacesaver spare is a different section/profile to the running wheels/tyres but the rolling diameter is the same.

You would only get transmission windup if you had a different circumference across an axle or possibly from front to back. The combinations of wheel diameter, tyre width and profile that LR specify will all give the same rolling circumference. If you stray outside of these then you will get the wrong speedo reading