Gas

Has anyone tried to run regular gas in their non-turbocharged min? If so, what happened. Seems like it might be a problem with it's 10.x:1 compression ratio.

Um, first off, the S is supercharged and it's actually MUCH pickier about gas than the Cooper due to the boost. Running regular won't really hurt anything because the computer will retard the timing to prevent detonation. This will KILL your performance and milage though. Not a good idea.

When I was driving across the country I was hung up in Iowa with only 89 for miles so I had to bite the bullet and get a couple gallons. My mileage for those couple gallons was significantly lower than the rest of the trip and power loss was noticable.

Shows how much I know about Minis!! I guess I should have figured that out by how they sound. Someone told me they were turbocharged, seemed reasonable to me, and I never questioned it. There a lots of Turbocharged engines around, but not many Supercharged ones that I know of. I guess they would have called them a Mini-T instead of a Mini-S if they had a Turbo, huh?

A technical question; Just how does the computer know the engine is detonating so it can retard timing? How do you sense detonation?

Knock sensor.

Hi,
New here, glad I did a search since amg already posted an answer on the topic-thanks amg.  I do have another question that searching did not answer; regarding installing a K&N air filter in my '03 Cooper, would that give better mileage?  Might that help the car run better on low test gas, or is low test or middle grade strictly out of the question? 
 
I get the best mileage when I ride my bicycle!
Thanks,
Tad

buy good gas,your mileage will decrees with low octane full,your engine
will ping,knock pre ignite not good.the money you will save on fuel you will lose on mileage.
Also possible engine damage.Buy a K&N and change your exaust to a less
restictive system.Dont over rev your engine,keep your tyres inflated to proper psi
and you will get good mpg.

My Thanks go out to you R.L. Dave,
I will continue to ride my bicycle to save on gas and feed my Mini only high test!  Both are "keepers" IMO.
Cheers,
Another Dave

Just Got my mini and the dealership didnt have the owners manual so I hadta call another dealership n have 'em special order it. So here's my question which gas is the  best for me to use? I've been putting in premium just to be on the safe side.

Use premium.  I have found out first hand that regular just doesn't cut it.  Performance and economy suffer noticably.  Octane boosters in regular don't seem to work as well as premium either.  Mid grade works better, but still not as good as premium.

Thanx. Makes sense. 

When I got my mini the dealer had filled it with regular gas and not premium.  I noticed it was jerking when you rolled up to a stop sign or when you were in reverse.  I read these forums and filled the tank with premium.  Wow what a noticeable difference.  More power and no more jerky stops.  The car runs much better. 

If you look on the fuel door, it says "Premium Fuel Only"