On my travels in the UK last year, I normally filled up my rental car at brand fuel stations, as they are far more common. I did use Tesco where they were available, due to their low cost. The only negative observations I had were the long waits at Tesco and no pay at the pump which would definitely speed up the process.
In Canada, supermarket fuel is not readily available and if it is, it is not much cheaper, as fuel here is about almost half the cost of what you pay in the UK.
As an aside, I use Shell V Power which in the highest octane level has no ethanol added which in my mind is a good thing.
The good and bad about ethanol
Let’s start with the good news. Ethanol is a cleaner fuel than gasoline, and it helps reduce emissions when mixed with gasoline. Plus the plant products used to make ethanol absorb some carbon dioxide as they grow. Finally, ethanol is an energy-positive fuel, meaning that you get more energy out of it than was used to produce the fuel, if you don’t count growing the plants in the first place.
On the downside, ethanol is less energy-dense than gasoline – meaning that there’s more energy in a gallon of gas than there is in a gallon of ethanol. In general, ethanol has about 33 percent less energy than gasoline. So, the more ethanol in the fuel, the worse the fuel economy you’re going to get. Gasoline with 10 percent ethanol yields about 3 percent less fuel economy than straight gas.
