When I bought my C230 sports coupe I was single and never had an empty wallet. Well...I got tired of being alone so I got married and had a baby. Now that I am no longer free as a bird, I find my self broke more than not. $4 a gallon for gas is hurting. Eventhough a sports coupe is too small for a family of three with one baby, I refuse to give up my coupe. To add to my present problem. I plan to keep this car for 10 years plus. I have never put anything less than 91 octane in my 2003 Benz but $50 to fill up is starting to become a real challenge. I've talked to someone that races cars but it all sounded like Greek to me. One thing I did understand was that I could put 87 octane in along with gas treatment. What happens in the long run when you put 87 octane in your tank?