Even if he did use bad gas, my car is still a 🍋 lemonpwait wait wait wait. This entire thread hinges on the WILDLY incorrect information somebody gave this owner on the fuel to use.
Do NOT, i repeat, do NOT, under any circumstances, use 85 octane fuel in a turbocharged engine. Holy crap. physics folks.
This is very basic "internal combustion engine 101" type stuff. Forced inductions requires higher octanes, otherwise you will destroy your motor in VERY short order, especially with a low-volume turbocharged engine like the 2.0L in the Discovery Sport.