Free gas??? Too bad.....

Definitely- Shell gas vs. Imperial (Esso) shows a consistent MPG gain.. I normally use Esso gas simply because it's convenient (there's a station right down the street from work) and because I'm on a fleet program where I get a discount on all Esso gas purchases. Recently, since the gas prices have come down to a bit more reasonable level, I decided to try an extended test with Shell V-Power premium gas and over the last 5 or so tankfuls, I'm averaging 4.6L/100km in my Classic Prius, in a temperature range of -5 to -15 C.. This is actually *better* than my summer mileage. Some of this I can attribute to the Michelin X-Ice tires, which I chose to be "minus sized" width, but higher profile for better snow performance and lower rolling resistance, but this accounted for my expected winter mileage of about 5.5-5.6L/100km with Esso winter gas formulation going down to nearly summer mileage of 5.1-5.3 L/100km (I normally get 4.8-5.0 in the summer), so the only explanation for the 4.6 that I've been seeing for the past few tanks has got to be the Shell V-Power gas..

I know that the normal explanation is that Premium fuel actually contains less energy, and certainly, the other times I've tried other brands of premium fuel, I didn't notice any difference, but there's something about Shell gas that doesn't fit the conventional mold..

 

My first fill up after the dealer tank calculated out about 6 mpg less than the MFD showed. I suspect it wasn't quite filled up initially. The next tank calculated much closer to the MFD value.

fd