The K75S has an 11.0 : 1 compression ratio, which is probably the reason why BMW indicated an unleaded fuel with a premium RON was required. I am just wondering if the initial premise is still valid considering the quality of fuel nowadays produced and considering the fact that many modern day engines have much higher compression ratios and operate knock-free without the pre-ignition problems BMW wanted to avoid in circa 1993.
I am wondering if anyone out there has been refuelling and riding their late BMW with regular gasoline without glitches?
Why do I ask? Up here in Canada, Super/Premium high octane fuel can easily be upwards of 10 - 15 cents per litre more than Regular which can add up to 60 cents on the gallon. Fuel in Montreal is bordering on $1.65 per litre for Premium/Super, that's $6.25 per US gallon.
Any thoughts on whether the theory of Super for a late model BMW might be obsolete.