Humans ask each other silly questions all the time: a human confronted with a question like this would either blurb out a bad response like "walk" without thinking before realizing what they are suggesting, or pause and respond with "to get your car washed, you need to get it there so you must drive".

Now, humans, other than not even thinking (which is really similar to how basic LLMs work), can easily fall victim to context too: if your boss, who never pranks you like this, asked you to take his car to a car wash, and asked if you'll walk or drive but to consider the environmental impact, you might get stumped and respond wrong too.

(and if it's flat or downhill, you might even push the car for 50m ;))