Nice. That explains it haha.

Thanks for the interesting reply. I thought long and hard about paying the extra premium for the fuel but came to the conclusion that, as I don't do a high mileage, it was worth doing because I read somewhere that it helps keep the injectors clean.

Hi, I drove 141 miles into Scotland from England on more-or-less clear roads last week. According to the consumption and distance covered I achieved 64 mpg! I am amazed at that figure - I used stop-start and eco mode and used Shell v-power fuel and cruise control wherever practical.

Sorry but I simply don't believe you.

Some years ago I had a BMW 120i as a loan car whilst my 118D was waiting for a new battery (warranty). Had it from Friday through to late Monday and did probably 200 miles over the weekend. Nice car but the mpg was poor, it averaged about 34 mpg. Compare that to the 47 mpg I was getting from the 118D and you will see why I say poor.

HJ's real mpg for the 120i is 34 mpg, exactly what I managed. HJ's real mpg for a 320i is 33 mpg 1/2 of what you claim which is why I question your accuracy.

On our twice a year trip to Scotland our most economical car has been the Golf TDi. Over the wek it would manage a true 57 mpg but on the long run it would be nearer 60 mpg. There is no way on this planet a 320i would beat that.

As for "I used stop-start" that is irrelevant on a drive on "clear roads" since you don't stop.

Looks as if someone put some of that magic snake oil in while your back was turned ....

Two points on this topic.

1. Using cruise control may only help economy a little, but using speed limiter really works. If you set the car to a maximum of say 75mph and let the car do its own thing whilst keeping the pedal in roughly the same position means the car takes advantage of the downward bits to improve economy without speeding up and you can regulate the acceleration up a hill to maintain speed,

2. A single motorway journey of say 120 miles with minimal off motorway driving could very easily produce 64mpg in many cars. My E350CDi, is a large, heavy estate car and whilst diesel makes the economy bearable, regular urban driving produces nothing better than 30mpg on average.

My most recent long trip of 711 miles on one tank of fuel equated to 43.3mpg. Much of this was spent at a speed limiter maximum of about 73mph (according to GPS), but signifcant portions were urban driving, or country roads with lots of speeding up and slowing down which affects economy. I know that 73mph on a flat motorway for ten miles will easily give me 60mpg - so why not a 2.0 BMW with Efficient Dynamics?

Can't claim to know the 320i M-sport personally. However, my last car (2012 Avensis 2.2 Touring Sport) averaged ~ 42mpg over it's life with me (& which fits in pretty well with HJ Real MPG for it)

An Avensis 2,2 is a diesel and should do that, the OP is talking about a petrol car.

Owned an E46 and E90 with this engine and neither could get close to this figure. I also doubt your accuracy either that or you’ve missed the d out on your model description. A 320d M-sport would do what you’re claiming with a light right foot but you’d be in the Guinness book of records if you managed it in a petrol.

From my personal experience with a 118D (a lighter car than any 3 series) you would never get over 60 mpg unless you drove at stupidly dangerous slow speeds which would annoy all other road users.

Looking back at my records from the 118D the best mpg I ever achieved in that car was a trip to Thurock (to pick up a gearbox) via the M1 and M25 early one Saturday morning (little traffic) and returning via the M25, A11, A14 and A1 (picking up tyres at Peterborough), decent traffic, a round trip of about 400 miles. The mpg for the trip was about 57 mpg. No cruise control on the car and just me in it plus the gearbox and 4 tyres on the way back.

When I talk about figures I have managed in the past I have been driving at as close to the speed limits as traffic would allow safely and overtaking when safe to do so.

CRV could break 60mpg on a run with care but without being ridiculous about it and the Avensis 1.8 petrol just returned 51.8mpg on a shopping expedition to Glasgow.

I don't know if these are round trip figures but if they are one direction i.e. into Glasgow they are meaningless.

Take my old commute in the 1.4 TSi Leon. The dash would show 60 mpg on a regular basis for my 15 mile run into work but the trip home would be in the mid 40's on a good day. Used to take about 30 minutes each way and the only holdup I would encounter (on virtually every trip) was crossing the M1 junction.

So why the difference in the two journeys. Obviously weather makes a difference but in truth I never took much notice unless it snowed. As I said traffic was pretty consistent so nothing there. The major factor was elevation. We used to live at 600 ft above sea level and the office was only 100 ft above sea level. So it was pretty much downhill all the way there and uphill all the way home.

Since Glasgow is a port on the Clyde I think its fair to assume its close to sea level. If you live at a decent height your trip would have the advantage my commute into work had.

Another example, went into Derbyshire to visit the Longshaw estate, a National Trust property. From there we went down to Baslow, about 5 miles. The elevation difference is about 750 feet. When we got to Baslow I was totally p155ed off, the display in the Leon had just gone over 190 mpg, was hoping to get 200 (in truth I think it went to - - - if it did that.

So without telling any fibs I could say that the Leon regularly did 60 mpg on my way to work and over 190 mpg on a Derbyshire day out. But since they would be totally meaningless I don't, I only quote figures that other people could hope to match in their life over a decent period.

I know that 73mph on a flat motorway for ten miles will easily give me 60mpg - so why not a 2.0 BMW with Efficient Dynamics?

Simple answer, your is a diesel and as you say 60 mpg in those conditions should be possible. But the OP's 2.0 BMW is a petrol which would make it impossible.