Xi'an is a city in Shaanxi province, China.
Direction East Towards Weinan, Shaolin Temple, Zhengzhou
You can take bus 213 from the south-east corner of the south gate. It takes more than one hour, but takes you straight to the motorway outside of the motorway ring. It's a little tricky to remember when to leave the bus. After about 1 hour, it crosses the motorway from south to north, then goes parallel for a while (you can see the motorway most of the time). Then it turns right. As soon as you see the green motorway signs, get off the bus and walk up the ramp.
Direction South Towards Chongqing
Take a bus from downtown Xian to a bus stop near the toll booth at highway G65 (around 30 minutes by bus from city center). Just west/next to the Sanzhou Cemetery is a big toll booth. The toll employees were okay with hitchhiking in front of the toll booth. There is some place to stop cars and Worldhitchhiker found a car within 15 minutes to get out of Xi'an (October 2019). The toll booth is not on Google Maps. Use the Chinese app A-Map (also known as Gouda app; how to download) to find the best connection to get to the toll booth. All toll booths in China are on A-Map, you need to zoom in to see the orange icon for a toll booth.