Yes, I'm cheap. Would bad things happen if I bought an FJ Cruiser and used regular gas when it says to use premium? The $.20/gallon difference will add up... As long as it doesn't hurt the vehicle, I'm ok if the cheap gas means less power...

It is not recommended... if the motor is designed for premium, you must use premium. Premium fuel has a higher octane rating, octane is the measure of the fuels resistance to detonation. Your engine must have very high compression which requires premium.

Use of regular gas may result in shorter engine life, rough idle complaints, or even a knocking condition. If the dealer sends your fuel for analysis after a engine failure... they have the right to cancel your engine warranty.

yes you can, new vehicles have knock sensors that adjust the timing to compensate for lower octane grades to prevent knocking.