The AI is interpreting it in the only way that makes sense, the car is already at the car wash, should you take a 2nd car to the car wash 50 meters away or walk.
It should just respond "this question doesn't make any sense, can you rephrase it or add additional information"
“I want to wash my car. The car wash is 50 meters away. Should I walk or drive?”
The goal is clearly stated in the very first sentence. A valid solution is already given in the second sentence. The third sentence only seems tricky because the answer is so painfully obvious that it feels like a trick.
Where is the car that you want to wash?
Ask a human that question randomly and see how they respond.