I just took another quiz that was basically the same subject but completely different answers... leading me to believe that both are arbitrary. For example, Mexico City was #1 on that list, it's #8 here. New Delhi, Johannesburg, Nairobi, Milan, Beijing and Shenzen were all top 7 or 8 on that list. None of them are on this list at all. I don't think Tokyo was on that list, but here it's #1. Sao Paulo #3 and Bangkok #4 were also not included on the other list. I complained about Manila not being included on that list, though it appears here. Both lists omit Cairo, arguably among the worst places to drive on Earth.