Squeals while I am driving
 

I drove a short distance to the gas station then a short distance back home. 15 minutes later, I went back to my car to leave and started to reverse. I heard squeals almost exactly the same noise as my brakes squealing. It did that for the 1 mile I was driving from 1-40mph. It did it no matter how slow or fast I was going. Same volume, same sound. Sounds Just like brake squeal, but I am not stepping on the brakes.
Does it in Neutral. Does it in gear. Accelerating, Decelerating.

Hand brake is all the way down. No CEL. Any idea's?

ProjectM96, does the squealing stops when you touch the brake pedal...?

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Sounds like your accessory belt / tensioner / idler rollers / water pump could be the cause.
Or it could be your AOS failing....

The easiest wat to check the accessories is to remove the belt and run the engine for no more than 30 - 40 seconds. If the noise goes away, closer inspections of the tensioning / idler roller bearings or water pump is in order.
Driving with a problem with any of the above is not a good idea.

Re the AOS, remove the oil fill screw cap and see if there is a suction - if the cap is difficult to remove, the AOS is failing.

Water pump, maybe. Remove the engine panel behind the seats. Start the engine and listen for where the sound is coming from. If you can identify it, there you go. Use a stethoscope or a piece of tubing at every component to narrow down where the sound is coming from. If you can't identify the source, take belt off and run the motor briefly. If the sound goes away, its something driven by the belt. Grab the water pump pulley and push it back and forth. If there is any noticeable play, or leakage, its bad.

Stone in the one of the brake's dust sheilds?

Update. Sound is coming from driver side front of car. I put the window down and stuck my head out. The sound was definitely coming from that wheel. Probably something to do with brakes or rotors.

I heard there was a tin metal sensor that touches the metal to make a squeal sound as a warning that it needs new brake pads.

Sometimes yes, sometimes the noise goes away when I hit the brakes. I just drove again and there was no squeal.

I had this issue in another car sometime ago. Took the wheel out and poked around to find a small stone stuck between the pad and the rotor. Narrowed it to that as I saw a scratch line running on the rotor all around. Once it came off the sound went away.

My Boxster sometimes makes a "woooooo" sound from the fuel filler door area and it sounds like that is the general vicinity of your noise too. The other suggestions made in this thread are on target but if they don't pan out it might be the fuel tank vent system. There are a couple of electrically operated valves near the fuel filler door behind the inner fender liner. Some people have replaced those valves and fixed the sound but I'm not totally sure your noise is the same thing. I bring it up in case the more logical sources don't seem to be the cause.

if you have the OEM brakes, then no metal sensor. porsche doesn't use that in their brake pads. instead, they have a electronic brake sensor that will light up in the dashboard warning lights. as suggested, check for a small rock or pebble. or give it a good power wash to see if it breaks it up. does the rotor look warped?