Originally Posted by John@BMW
Yep, condensation drainage from AC is hitting the exhaust. The best thing to do is pull off the panel under the trans and either reroute the drain line or add another length of hose to make it drain somewhere NOT over the exhaust.
Does it hurt anything if we don't? I'm in Houston, TX, so we have extremely hot/humid weather and I get the sizzle even if I'm making my ~5 minute drive to work. The sound from mine sounds like it's coming from the front passenger side...