Best way to see shanghai In 15 hours

Hi there, I will have a 15 hours layover in pudong, and I really would like to go out and visit the city. I'm just a bit afraid as it is a huge city...was thinking to use the sightseeing bus but I know it doesn't run from the airport? What should I do? I really look for something not too stressful..otherwise I might just stay win the airport..thank you