[jatari]

I agree that it doesn't break any rules of the English language, that doesn't make it a valid question in everyday contexts though.

Ask a human that question randomly and see how they respond.

[mvdtnz]

Can you explain yourself? I can't see how this question doesn't make sense in any way.

[methyl]

Because to 99.9% people it’s obvious and fair to assume that person asking this question knows that you need a car to wash it. No one ever could ask this question not knowing this, so it implies some trick layer.