You get a lower gas mileage because it needs more fuel at one time to reach the maximum potential, and it still doesn't have very good performance.
Nothing happens, except your wallet will be lighter.
Depends... What does you owner's manual say? I currently drive an E-Class 320, and it requires Super Premium (91-92 Octane level). If I even try to use Premium instead of Super Premium, or even worse.... regular.... the sensors in my car know within a few seconds of turning on the car.
it could, read the owners manual that came with your car. it will say what kind is recommended, the octane levels in gas vary and if you go to low you could cause your engine to knock and soon after blow.
Yes, that is what Toyota recommends. Using Premium fuel will provide no benefits whatsoever and is a total waste of money.
You can use unleaded in a low compression engine such as the in-line 6 and the 260. But use a high octane unleaded instead of regular unleaded. If however you have the 289, I am not sure on this engine. The 289 HO will require the use of a VSRP additive at each fill up. If your 289 has hardened valve seats and does not require a VSRP additive, you can simply switch to Shell V-Power (98 octane) or Shell Unleaded (95 octane) straight away. If you find that your Mustang tends to run hot then you will need to readjust the fuel/air mixture on the carburetor for the modern unleaded fuel.You can use unleaded in a low compression engine such as the in-line 6 and the 260. But use a high octane unleaded instead of regular unleaded. If however you have the 289, I am not sure on this engine. The 289 HO will require the use of a VSRP additive at each fill up. If your 289 has hardened valve seats and does not require a VSRP additive, you can simply switch to Shell V-Power (98 octane) or Shell Unleaded (95 octane) straight away. If you find that your Mustang tends to run hot then you will need to readjust the fuel/air mixture on the carburetor for the modern unleaded fuel.
Premium gasoline is unleaded. Yes, you can use it, although there may be no actual benefit in it.
You can but your ignition timing and cam timing, if you have adjustable cams will be retarded to stop detonation. Fuel economy and performance will drop.
Plus (89 or 91 octane) will nor harm the engine or fuel system on an engine thats call for 87 octane.Plus (89 or 91 octane) will nor harm the engine or fuel system on an engine thats call for 87 octane.
For a real answer check out this http://www.cartalk.com/content/features/premium/questions.html Their answer is a qualified yes, it is OK to use regular in modern cars. But read the all the details in the link above.
you will run the risk of pre-detonation, which can potentially damage the engine, most have knock sensors which will pull back the timing to compensate reducing power and efficiency of the engine.
This all depends on the compression of your cars pistons, If you have anything over 10 and you opt. for regular Unleaded you might get pre-ignition in your cylinders which will cause a "PINGING" or "KNOCKING" sound usually high-end cars call for higher octane gas. So unless your car calls for premium fuel stick to regular and save a few bucks.
... use it for what? Or if you use regular gas instead of what? If you ask this question again - with some more information saying exactly what you want to know - someone may be able to give you a better answer than this one!