E46Fanatics - View Single Post - Premium Gas or Unleaded for -04 330ci-
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Old 04-08-2012, 04:00 PM   #42
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Join Date: Mar 2012
Location: Estonia
Posts: 681
My Ride: 2002 BMW 325Ci
Premium gas becomes more important at low altitudes, in cold weather, or with modded cars. On a bone stock e46 at say 5000 feet altitude regular gas is probably the same.

On a cold day at sea level that premium gas is of much more value.

Any car with turbo or supercharger must use the highest octane gas available. If you have a CAI you might only see its effect with high octane gas.

Essentially the more Oxygen is in your engine the more important Octane becomes.
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