I live in Xi'An and have learnt that the safest seat in a taxi is right behind the driver. A large percentage of taxi drivers here would be considered reckless by western standards, but most are not reckless enough to risk their own personal safety, so sitting right behind them makes you as safe as them. In other words, taxi drivers don't mind getting t-boned on the passenger door, which is where you are most likely to sit, but are reluctant to get drilled on their own door. So, sit behind them.

And, always get out of the taxi on the passenger door side.