[CCroker]

According to the manual on my 03 S, it says 91 RON which would be 93 at most pumps as RON is not the stated measure at US filling stations. MINIs will run there best ( performance and fuel wise ) at the better grade. As posted above the differences in prices amount to $1.20 to $2.40 a tank. Fuel injection cleaners cost $5-$6 a can. Plugs cost on average $10 each ($40) and oil and filter costs $40. You will also realize a 1-3 mpg cut in mileage increasing by 1% over each month using the lower grade fuel. So, if you fill up 3 times a week, you will realize an equalization in costs. But, if you fill up just once a week, the increased maintenance will overcome the difference of the cheaper fuel to the more costly correct fuel. If you do your own manintenance you will save again, but if you rely on a dealer or a service center, you've lost $ again. Do what the manual says, but do the services at half the intervals. 7.5K instead of 15K and replace plugs every 2 years not 100K. Plugs are only guarenteed by the manufactures for 2 years. Clean oil lubes better for mpg and use a good synthetic. Don't forget the transmission, manual says for life ( it does have a drain and fill plug). And tires, the most forgotten thing on the ground. Just because the monitor isn't lit doesn't mean you shouldn't check them ( fuel really gets wasted there). Do your maintenance a little more often and you will get more from the MINI and won't have anything to complain about. The MINI is rated #7 in the top 10 Green cars in the US. I can get 28 in town and 38 on highway and still punch it now and then.