the price of gas octain levels are not that different for me because i use only shell gas. I read this forum to find a answer and one simple answer was not found. for me. I use my shell Drive for 5 gas card. boom 5 cents off every gallon. than my shell rewards card. which i have been able to get it up to 10 cents off every gallon. so the two combined i save 15 cents a gallon. so price to me makes no difference. i was looking for a real answer to the op question. I will prob do the test myself. i can get 400 miles to a tank with reg gas. i will fill up next time with with shells V POWER gas and see how far i can go then.