I'm not entirely sure where it's coming from as I haven't gone under the car to check it out, but it seems to be coming from just in front of the rear wheels. What could be causing a hissing sound back there? I have a 95 SE (completely stock). Any ideas?

 

...A SNAKE HIDING IN THE WHEEL WELL?

 

It could be the tires or maybe the wheel bearings

 

If the car is running at idle and you're sticking your head under there, it could simply be the fuel pump.

Try this: With the car off, turn the ingnition switch to the "on" position without starting the engine. You should hear a hissing sound for a couple seconds, as the fuel pump primes - is this the sound you're hearing? It sounds the same, but continuous when the car is running.

If that's not it, you may have an exhaust leak - inspect the muffler and b-pipe for holes/cracks - if necessary, you may be able to patch it with an exhaust patch kit from your local auto parts store. If it's really bad, you may need to replace either the b-pipe or muffler.

 

could be a small air leak? i think u would notice that though