Fuel consumption observations..

shown73

Just finished one of my periodic trips to Germany, 5year old Mondeo, 1.8. There and back about 1000 miles.
Outward trip, using normal petrol, as recommended in handbook, pretty steady driving, worked out at about 39mpg overall, according to the fuel computer. Whilst there, noticed that German pumps were dispensing something termed "E10" petrol, and its causing a bit of an uproar over there, as not all cars are suitable, and info on which ones are is pretty sketchy. Super plus is still available, at a price, so I stuck to that, just in case.
On the return trip, using super plus, conditions pretty much identical, same driving style, weather, weight, etc., consumption was 42 overall. Topped up again in Dover, going back to 95 oct, due to the price difference, and drove home. Consumption 39mpg.
Just thought this was worth sharing, since this sort of topic does crop up regularly, and this was more or less a controlled experiment as it turned out. Not scientific in the pure sense, maybe, but pretty accurate all the same.

property.advert

The E10 is ethanol 10% I think.

Was it uphill going there and downhill coming back ?

cardinalbiggles

property.advert wrote: »

The E10 is ethanol 10% I think.

Was it uphill going there and downhill coming back ?

You wont be getting 10% nationally here anytime soon. Most storage tanks in the UK were all changed to fibreglass which only tolerates 7% ethanol before starting to dissolve.

They are being replaced now though back to metal tanks at new sites.

forgotmyname

Shame you went by the trip computer which is not very accurate. It only displays the average consumption
so the long journey would slowly increase the average mpg.

A trip to blackpool and back increased my average mpg from 38 to 50+. Short local journeys soon dropped that
back down though. Ended up at 38mpg average.

attila_

Noticed this on both passat and ibiza: if i start my journey with no traffic and get a good mpg at the start, then later on even if i get stuck in traffic or drive hard the mpg avwrage still looks good....

If at the start of the journey i am stuck in traffic or drive hard then drive smoothly the average mpg wont be as good. Could just be a vag thing....

Did ure return journey start on a flat open road and tame speed?

Could possibly be the fuel with a higher octane number though. I use millers ecomax which inctease cetane by 2 and sure if it makes any difference tbh.

esuhl

shown73 wrote: »

Just finished one of my periodic trips... There and back about 1000 miles.
Outward trip... worked out at about 39mpg...

On the return trip, using super plus... consumption was 42 {mpg} overall.

So the "super plus" petrol took you about 7.7% further per unit of volume. But what was the difference in price?

If the "super plus" cost less than 7.7% more, then it would make sense to buy that, otherwise it would be cheaper to get the lower octane fuel.

Update: According to PetrolPrices.com (showing min/max/avg petrol prices in the UK), the difference in price between standard and "super" petrol is around 3.5 to 5.5 per cent - so (assuming the results of this non-scientific test are valid), then it would be cheaper to use the higher octane petrol.

shown73

Didn't work out the price, that's interesting. More important to me though, it meant that I could get from start point to Dunkirk without having white knuckles for the last 50 miles, or filling up again at motorway prices. So, it definitely used less of the super-plus. I zeroed the computer at the start, and, as usual, mpg gradually increased as the journey progressed, but it doesn't take long to get to optimum, it doesn't continue to increase. Goes up and down according to speed and hills, etc., but pretty consistent.
There has often been discussions on here about the mileage benefits of higher grade petrol, or otherwise, but this is the first time I've really proved it, to my surprise. Never had a car with one of these widgets before.