I put gas in my 9-3 for the first time last night (dealership had filled it when I took delivery last Friday). The sales guy said they recommended mid grade (which around here is 89 octane). After reading some threads here, I decided to pay the extra 15 cents and put 93 in. However, while driving home, I swear the engine "felt" rougher...and it seemed to just not idle as smoothly as before. Could it be that the car is just adjusting to the higher octane, and it will smooth out later? I'm assuming they filled it with 89 (sheesh, they probably put 87 in it to save money), but I've never had a car run rougher by putting in higher octane gas before. Am I crazy?