I own a 2004 BMW 530i and it recommends using premium gas. Is this for performance only or will other grades of gas damage the vehicle?
Does your manual say “recommended” or “required”? Me, I’d stick with premium in a BMW.
Even if it says “recommended” that only indicates that the engine’s systems have the ability to compensate for lower octane’s propensity to ping, it does not mean optimum performance will be achieved with regular. This is not an economy car, it’s a performance car. To get proper peformance you’re better to stick with premium.
If it says “required” then you have no choice but to use premium or risk engine damage.
those words should also be on the gas cap.
You’ll likely get lower fuel economy and performance from your engine, so the trade off between 87 and 91+ in terms of cost per mile will likely lead you to give it high octane