The answer is yes, assuming everything is working right the system will compensate for the regular gas. However, you are TOTALLY missing the point of what everyone in this thread is saying.

You will be saving, MAX, like $2 a tank. For that HUUUUGE savings you will be taxing your cylinders, head, cooling system, knock sensor, etc. TOTALLY unnecessarily by forcing teh engine to retard the timing, lean the mixture, and run hot.

Why would you want to do this? Do you like saving $2 now to spend $500 down the road? Its your car, but I would highly recommend against it.

Oh, and as for newer cars and engines. This is a turbo, not a regular v6 or something. You are running under HIGH compression pretty much all the time, and under compression octane rating becomes MORE important since lower octanes can cause pinging and pre-detonation under compression.

What you see and what is actually happening are two totally different things. That Boxster might SEEM to just get a lose a few MPG with higher octane, but I will bet cash money the engine is suffering all the aforementioned behind teh scenes with the lower octane.

good luck,
rt