My car has been making this really bad rattling sound, so l looked under my car and found that the exhaust system is vibrating really bad and is rusted really bad. Is it normal for the exhaust to be rusty? Also what should l do?

l have a 99 Subaru Impreza.

yes it is normal, get it fixed

Yep. unfortunately they rust out. Heat and moisture.

Usually the rattling is caused by a loose heat shield. Sometimes a clamp can be added to tighten it up, sometimes just putting a crimp in the shield will stop it from rattling.

all most 7 years ,exhaust are pretty easy to change.first make sure it is not a bracket holding it up to frame. If you do have a hole you can buy repair tape to wrap around hole.It looks like duct tape. If your low on cash it could last you up to a year.

Yes rust is common.hell some of the newer Subarus already have rust on the exhaust.

What u will have to do is pinpoint where the rattling is coming from.look for anywhere that metal is close to metal such as where the exhaust runs by the transmission. You may be able to get away with just upgrading/replacing ur rubber exhaust hangars as those r usually what will wear out first which lets the exhaust move more than it used to new.

If its a heatshield that is loose, hopefully a screw or bolt just came out because of the age of the car & u can replace that. You may be able to get the heatshield welded down if that does not work.

Anyways, those r the 2 usual things to make it start rattling first.spend some time under the car & try to move it around a little to see if any metal is touching.