Surprised at that 60mph average figure John, thought you'd have got more?.

Surprised at that 60mph average figure John, thought you'd have got more?.

Odd how we differ; that looks high to me. What speed was being maintained on the M/way?

At the risk of incriminating myself, what was displayed on the speedometer can be deduced from the info in my post. I used to have a portable sat nav which indicated one or two mph lower than the speedo which was probably a truer speed. I have read a high miler's post that setting the cruise to 80mph is unlikely to trigger a camera, but I am a bit more cautious. Three speeding fines and one awareness course (jeez - that was a farce - but revealed astonishing ignorance amongst my fellow culprits) in my 54yrs of driving is quite enough, thank you.

Surely it's basic knowledge that at speeds much above 50mph, fuel consumption starts to increase noticeably, mainly due to wind resistance but also because the engine will probably be past the peak of its torque curve. I also suspect that the small engine in John-F's tall vehicle may be struggling a bit more than some others might ?

Car was the 1.2 Fabia. Average about same as OP but very noticeable how the average mileage clicked upwards during the long 50 or 60 restrictions where SMART motorway is being installed

Back in about 2014 works took place to install Smart motorway on the length the wife used on her commute, approx. 20 miles of which 15 miles was on the motorway. The limit dropped form 70 mph to 50 mph but her journey time changed little, 5 minutes or less. But her fuel usage dropped considerably, the average mpg of the Ceed diesel was about 50 mpg for the commute pre road works, during them it dropped to almost 60 mpg.

I have a Skoda Superb 1.4 tsi direct injection turbo petrol that is a heavy/large car but is pretty aerodynamic. As I've realised during lockdown with local driving it gets mid/late 30's mpg. However on a long run including motorway driving (70mph@2400rpm) it gets mid/late 40's mpg.

On our twice a year trip the Scotland the Superb 1.4 TSi 150 PS would average about 53 mpg for the week, a calculated figure, not one taken from the dash display. That is lamost as good as we got form diesels in the past. At an indicated 73 mph (true 70 mph) it was doing about 2200 rpm.

The Leon TSi 140 PS we had before the Superb would average about 49 mpg for the week (again calculated), considering the Superb was a bigger and heavier car yet better on fuel I was surprised. After a few trips and the figures for the Superb were consitent I put the better mpg down to the facts that the Superb at DCT (shuts off 2 cylinders at a light load) and better aerodynamics.

From 2013 to 2019 I ran an x-type 2.0 diesel. Usual mpg was about 46 mpg in local use. On my (then) annual trip to Andorra - mix of local, motorway, autoroute and mountain roads) my mpg was about 56 mpg, which I thought was pretty good.

My current car,, a sub-£1000 cheapo - Chevrolet (Daewoo) Lacetti 1.6 estate - does about 35 mpg around town in lockdown rules and about 45 mpg in longer runs. Nothing like as good as the £7,000 Baleno I owned for 9 months in 2020 (returned under CRA 2015 rejection law) at 50+ mpg but costing out the whole ownership costs, my cheapo car wins. And, should it become necessary, i can jettison it without too much regret.

(Actually, I would have regret. The lacetti is very practical and more comfortable than either the x-type or the Baleno).