The garage door was open behind him and my friend noticed liquid running down the driveway. He went over to tell his neighbor that he had just plugged the gas tank on his car. His neighbor hadn’t even noticed.
Consider the volume of a normal gun silencer/suppressor. Consider the volume of a house.
My friend didn’t say whether the mower his neighbor was working on was running or not. If it wasn’t, I would have thought the sound of that bullet piercing the gas tank would have made quite a thunk.