There was no mention of this during the booking. It wasn't until I saw the charge on my credit card statement that I found out about an extra fee of around 100 yuan. After 10 days of inquiry, the car rental company claimed it was a special location pickup fee. They couldn't explain what constitutes a special location. I picked up the car at the airport, which I guess is pretty special! It feels unfair, even though the amount isn’t much, it's still frustrating. Seems like I need to understand the rules better next time.