There is a difference between peak MPG and Average.

Average is affected by where you drive and your driving style.

Peak is easy to find out, just do a steady speed somewhere between 56mph and 70 then reset the trip computer. 56 is usually the optimum speed, i remember reading somewhere above that figure aerodynamics play a bigger part than weight, but it depends on the cars gearing. I did my 2004 4.4V8 at 65mph as at that speed the suspension lowers (should slightly reduce the frontal silhouette) it also puts the revs just over 2000rpm, which the book says is that engines most economical rev range (2-3000)

Average means less when comparing our cars on forums etc. Because i could drive my car along a given route then hand over to someone else and they could get a different figure, just because of their driving style.

it's why the whole EU drive cycle thing was introduced, because manufacturers would simply quote guesstimated figures, lie or pick the optimum fuel load, vehicle load, optimum and do it on a track with a slightly downhill slope when there was a tail wind and quote that. The figures you see in brochures now, give you a good like for like comparison between different cars, but the figure might not be exactly what you personally get from a car.

Just done 2 days off roading in Wales, did about 620miles in total with the trip there and back and mine did 10.6mpg, mostly on petrol as they don't seem to use LPG in mid Wales...

Fully loaded, didn't hang about, lots of heavy bit's and 32" tyres....

That 10.6 is very accurate as my speedo is now just about spot on.... remember all other mpg's are based on speedo readings and will be about 10% high...

You don't buy one of these for economy....  Pete
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2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Sold
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand Sold
2002 L322 Vogue 4.4 V8 Epson Green (Fatty Offroader) Sold
-Click for Project Fatty off roader-

I've just managed 32 mpg over a 270 mile trip on A-roads and motorways. The average speed was 63 mph so not a truck slipstreaming effort. The cruise control cannot match that figure.

Just to comment about the 'old' 56mph thing. It was a part of the EU test to run at a constant 90 kph to provide a comparison fuel economy figure. Never mind that it was on a rolling road with no air resistance etc. As a result car manufacturers modified the fuelling maps to make their vehicles to run very very lean air:fuel ratios at those exact revs. Hence most cars of that period are more economical at that speed. Of course the engine will be running less optimally too.

Nick 2019 D5 HSE Lux SDV6 Indus
55 D3 SE
98 MX5 1.8 RS
gone 17 older variants of FFRR

I was getting 2 MPG on Monday during my trip to Reading, was fun!

2 mpg is much more fun. Life is too short, although it feels the opposite, for 32mpg.

Nick 2019 D5 HSE Lux SDV6 Indus
55 D3 SE
98 MX5 1.8 RS
gone 17 older variants of FFRR

Nick Ground wrote:

I've just managed 32 mpg over a 270 mile trip on A-roads and motorways. The average speed was 63 mph so not a truck slipstreaming effort. The cruise control cannot match that figure.

Just to comment about the 'old' 56mph thing. It was a part of the EU test to run at a constant 90 kph to provide a comparison fuel economy figure. Never mind that it was on a rolling road with no air resistance etc. As a result car manufacturers modified the fuelling maps to make their vehicles to run very very lean air:fuel ratios at those exact revs. Hence most cars of that period are more economical at that speed. Of course the engine will be running less optimally too.

Nick