On 2/24/2019 at 8:27 AM, Jonson said:

I definitely get 3 or 4 mpg less from tesco regular compared to shell regular. Momentum gave me equivalent to shell regular, v power no improvement over regular.

Have you got a proper record of mileage and quantity bought at every fill?

49 minutes ago, David73 said:

Have you got a proper record of mileage and quantity bought at every fill?

Yes indeed 

Tesco's regular in my ecoboost focus 140hp for last 4.5 years. No issues 

Tesco momentum dose seem to pay for itself over tesco standard. I get an increase of 10% or 4mpg over tesco standard. After flicking back and forth just to confirm the numbers stack up and are repeatable. I now run solely on momentum. 

Not a Fiesta (1 litre Focus ecoboost, 6 speed, 13 plate) but I am curious/sad enough to keep a spreadsheet of my fuel use, mostly to see how the car's MPG compares with calculated values.  In all cases I try to drive until as empty as possible and refuel until the nozzle automatically shuts off. 

The average speed will give you an idea of the type of driving, which is mostly town (Edinburgh) with some faster roads occasionally.  The car's MPG is always higher than the calculated value.  Sometimes it's way off, sometimes they are quite close.   It's definitely a lot more economical at speed. The last line corresponds to a lot of 60 & 70 mph driving from Edinburgh to Campbeltown and back, for example.

What I don't see is any particular consistent improvement in economy from one particular fuel type or supplier.  I tried to use at least three tanks of fuel per supplier but this was not always possible (no V-Power in one station, only closest station was a Morrisons at that time etc).  The closest petrol stations to my house are a Shell and a Tesco, the closest to my work are BP and Sainsbury.  The car's handbook recommends BP regular so I thought I'd try that for a few tanks to see what happened.

I think driving style and journey type have a much greater effect than the fuel provider or octane rating (for this engine).  Really I ought to test by driving three tanks of, say, V-Power, at speed and then compare with Momentum, regular etc. I'd see a lot of lovely Highlands scenery but I don't have the luxury of time or spare cash to try!.

On ‎2‎/‎26‎/‎2019 at 5:57 PM, cjay1 said:

Tesco momentum dose seem to pay for itself over tesco standard. I get an increase of 10% or 4mpg over tesco standard. After flicking back and forth just to confirm the numbers stack up and are repeatable. I now run solely on momentum. 

I have a 140 ecoboost, and can only agree with this. Have a daily commute of a 50 mile round trip 4 times a week, about 70% on motorway or dual carriageway. Sit around 70 teh way to work, and on the way home I sit at about 80, and can easily finish the week with half a tank left when using momentum, compared to under a quarter when using Tesco regular. 

I'm a chemist and I've calculated that at least in Finland I'll always lose a bit of money when using RON98 gas instead of RON95 but since Ecoboosts are direct injection engines using better fuel means less carbon deposits. Here the price difference is about 4-6 per cent and the better fuel gives less Thant that better mileage. And the effectiveness of the gasoline has been calculated theoretically so technically it should be the best possible addition to the mileage possible.

Looking at the tech specs of momentum vs tesco 95 momentum is denser so possibly is more calorific? So possibly better mpg all other things being equal? 

www.greenergy.com/uploads/GcXQO6FIzF5E_99octane_2018.11.pdf

www.greenergy.com/uploads/EVAa0LGZyg8m_petrol_2018.11.pdf