I did the math on the difference out of pocket over the course of a year, since I've had my regular (87 octane) SUV that gets ~14mpg for the last 13 years.

If I were to switch to a premium (91 octane) SUV that gets 15-17mpg around town like the E70, I'd be paying US$150-$200 more per year. It's nothing... especially after spending so much on the car itself.

$44 regular weekly vs. $47.2 premium weekly (w/ slightly better mileage) = $166/year difference.

Unless you're coming from a Honda Civic instead of another SUV.