I stopped using premium fuel and got a huge dip in fuel economy - what do you think caused this?

I have an Hyundai Ioniq, which I've run exclusively on Shell fuels for the 5000 miles that I've had it. I was getting 60-62 mpg on the regular stuff, then put a tank of the V-Power in and got 64 mpg. I then switched back to the regular and I'm now getting only 53mpg. Is this likely an issue with the car, a bad fuel batch or just all the extra rain we've been having recently? The car appears to run fine.

Asked on 5 October 2017 by Craig Aye

Answered by Honest John
Mix of factors. But best to use V-Power all the time, not occasionally. That doesn't work.
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