I was a bit surprised on my first fill-up to see inside the fuel filler door a decal that recommended the use of premium octane fuel. When I first moved to Wyoming I noticed like all the Rocky Mountain states, it was common for premium fuel (regardless of brand) to be 91 octane and regular to be 85 octane. The owners manual strongly suggests the use of 93 octane in the 2.0 liter turbo engine. I was told because of the altitude where I live (6100 feet above sea level), it was not necessary to use 93 in any vehicle and 91 will work just fine. When I had a 2008 Corvette (now sold) I would use 91 octane (93 recommended) with no adverse effect as that was the highest octane available at most gas stations. Since I drive my 2018 Terrain much more than I drove my Corvette, the use of premium fuel at ~ 50 cents more than regular (85 octane in the Rocky mountain states) can become expensive. Does anyone else have experience with fuel grades on their 2.0 liter turbo engine?