2000 Dakota 4.7L exhaust issues
 

Got a '00 Dakota with the 4.7 in it. The exhaust has a small leak the muffler is rusted. Also, it has no tail pipe. I noticed it has been getting very poor mpg. Could that be the cause of it? I know with it being a v8 the mpg wont be fantastic, but still. Any info would be appreciated!