Can you switch from premium to regular gasoline?

Answer 1

Yes. Any vehicle that can run premium gasoline can run on regular. With that said, if your engine is such that it can benefit from premium gasoline, it will lose some of its performance.
Sure. All cars are designed to run on the lowest grade. only use the others if you really need extra Octane (engine knock)

if your car requires premium gas, then that' what it needs. If you try to run it on regular it might start to knock, spike and run poorly. This may even damage the engine.

If you really feel the urge to experiment, you can put some regular gas in and see what happens.

Start with 1/4 of regular and 3/4 of premium.

If it runs OK on that, even on hard acceleration, try 1/2 premium, 1/2 regular.

If it runs OK on that, even on hard acceleration, try 1/4 of premium and 3/4 of regular.

If it runs OK on that, even on hard acceleration, try all regular.