Bottomless definitely counts!
In that case the instance where I had fallen into a canal counts.
I squelched back to the car park where I stripped naked beside the car and then drove home wearing a short nylon waterproof which I keep in the boot - open at the front to take advantage of the car heater blowing warm air to dry me.
Apart from anything else it stopped me from getting the cloth car seat wet.
Just drove two days from Ohio to Florida. Because of the heavy holiday travel I couldn't drive totally nude as I have in the past but did drive it bottomless.
Why would traffic make you wear as shirt?
While I don't drive nude, I usually drive shirtless in warm weather, no matter how much traffic there is.