Last time I filled up with gas I decided to get a carwash as well (You know how convenient they make it right at the pump, plus $1.00 discount). Please save yourself the trouble of telling me how bad carwashes are for my paint, water to the ECU, etc. I drive a 1996 BMW 328i. The car is old enough that I don't care if I slowly destroy the paint going through the carwash. I'll take my chances on everything else.
Anyway, after I went through the carwash, I noticed that the little dor to the gas tank/gas cap area was open -- I forgot to close it after refueling

ghead I got off thecar and walked into the carwash area to find the gas cap (I had left it on the holding bracked inside the gas tank door, and it had obviously been thrown off by the water). I found it, made sure to dry the region right outside the tank, and put the cap on.
I will make sure to keep my tank as close to full as possible for a good while just in case some stuff was able to make it into the tank. The more gas I put in there, the thinner the "solution" becomes.
I prayed for the vehicle right after all this happened, and hope it is in God's plan that my car does not die. I am not going to have it checked out.
The weird thing is that the "Check Engine" indicator did not illuminate. I understand usually it does if one turns on the ignition while the gas cap is removed. Weird.