Experience With E10 Fuel

January 17, 2011

Last week I did my first long motorway trip in the Gen 3 Prius from Calais to Provence with an overnight stop half way.

On the first day I pulled into the first filling station we came across on the motorway and filled up with Shell 95-E10 (In case you haven’t come across it, this is 95octane plus 10% ethanol which has been available in France for a year or so). The terrain to our overnight stop was quite hilly and the weather was damp with temperatures around 6^oC. I set the cruise control for 75mph and, except when we were blocked by lorries overtaking each other, the speed was maintained for the whole day. The car did seem to be making heavy weather of the hills and the average mpg figure dropped as we went up hills and then recovered down the other side. Overall the mpg was 48.8 when we had to pull-in for a small amount of petrol to get us to the overnight stop. This time I put in normal 95octane and the change in the car was remarkable. It felt more responsive, went over the remaining hills with no trouble at all and the mpg reading ended the day at 52.1mpg.

At the start of the second day I filled up with supermarket 95, reset the trip recorder, and set off to do the rest of the journey. The terrain was not as hilly as day 1 and the weather was dry with temperatures about 12^oC. Again the cruise control was set for 75mph. This time though the car never felt as if it was struggling and the consumption was just on 59mpg when we left the motorway.

From the receipts I have calculated the actual consumption for the two days as 46.0mpg for day 1 and 56.0mpg for day 2. No doubt fewer hills and higher temperatures will have had some effect, but I am guessing that most of the difference between the two days is due to the fuel.

The DfT put out a consultation document last year about introducing 95-E10 to the UK. I have read a few comments on the web that it will be in the UK this year but have not been able to find anything on the DfT website to confirm this. The aim is to reduce emissions but if my results are typical the lower fuel consumption will more than wipe out the benefit of replacing petrol by ethanol. Has anyone else found the same effect?

January 17, 2011

Are you sure that E10 isn't already available at some UK stations?

I'm sure I've had a 'bad' tank of fuel or two recently where my mpg's and driveability have been reduced inline with your findings. I can't remember which brand I used to cause these odd experiences (maybe Esso?) but reading your findings made me wonder if I was alone in the UK?