Are any of you noticing a fuel economy impact running E10?

[Iamzod]

I know there has been loads of stuff in the press recently about E10 causing drops in economy but i've pretty much ignored it and not paid attention to MPG for months as i've really only done the odd run to the shop in my wifes car which has been running on the stuff since it appeared, had a bit of running around in the wife's car today however and it definitely seems quite a bit worse when I actually paid attention to the trip computer to what it used to be capable of.

It's an Octavia 2.0 FSI, Worksop to Pinxton via the M1 at at 65MPH resulted in a readout of 32 MPG, the same journey in reverse got a marginally better 34 MPG.

Spent about 45 mins in town too, 16 MPG.

Running around town used to average 23ish and motorway trips used to result in 40 - 43 MPG.

Anyone else seeing similar issues running this new E10 or is my wife's car simply broken?

 

[Iamzod]

Well, since the wife tested positive for Covid the day after starting this thread i've been doing literally all of the running around for the last week.

Wednesday morning came around & I managed to time it so i'd hit a shell station a few miles away from home with the car running on fumes so as an experiment I brimmed it with Shell Vpower whereas it's been filled with Shell E10 ever since they released it.

Going by the trip computer running a 3.6 mile portion of the same stretch of road from where I live to the nearest M1 junction on a pre-warmed engine with the cruise set at 50 i've got an increase in MPG displayed from 33.7MPG at 6.5c to 37.9MPG at 1.0c, it's only 1 run on each fuel of course but it's a dual clutch and given it was a clean run without having to brake or disengage cruise literally all I did was steer I can't see how there could have really been any other variables, it was a good bit colder too on the run with the higher figure.

 

[Iamzod]

3.6 mile portion?

You see there are loads of things that could severely affect such short journeys. How cold is the air temp? Cooler air temps are actually good for the car once warmed up. Even slight differences in traffic. Is your alternator working a bit harder from one run versus the other to top up the battery? How does your car react to 99 ron fuel?

My mpg doesn't stay the same from one 500 mile section to the next and can deviate by up to 10% even for the journeys made up of the same commute every day. I use odometer and fuel filled as the proper measure as the car computer is terrible at estimating mpg.

What people aren't doing are properly controlled large sample tests and that is why nothing I've seen is convincing.

Last car:

Current car:

Yep, 3.6 miles as it's a reliable 3.6 mile stretch of road where I know that I have to do nothing but steer which takes out variables like accelerating, braking & gear shifts, you just sit at a solid 50mph all slightly uphill.

It's a 50 limit with 3 cameras along it and is a fairly quiet stretch with little traffic interference unless you catch a HGV or Tractor.

I'm not going to repeat it on purpose of course but every time I traverse that stretch I might reset the trip and record mpg, and temperature out of interest.

And I know that the trip is terrible & tends to be optimistic but i'm looking at the variation rather than the outright figure.