Does it take long to go through customs to exit and enter the Shanghai pudong airport?

I have 16 hrs wait at the Pudong airport for my connecting flight. I am NZ citizen and flying to Frankfurt. To ease my long wait I wold like to go and see a little bit of SH. The organised tours do not pick up people from the airport and I can't make the time to any of the hotels they pick up from, but I can get a private pick up and drop off from the airport. How easy is for a tourist to exit and enter customs to go to downtown SH if is not with an organised tour? I wold love to go and see SHi for a few hours but am a bit concerned about how complex the exit and entry is. How far is SH from the Pudong airport? Thanks. NT