Recently, the use of in-vehicle navigation devices, such as PNDs (Personal or Portable Navigation Devices) has become pervasive, and the device functions have been rapidly expanded and updated. Unfortunately, drivers often have considerable difficulty using these complex technologies. To improve and optimize PND user interfaces, the present study suggested several display improvements for the turning point, which is one of the critical usability issues. Advanced Turn-By-Turn Display and Spatial Turning Sound were suggested to facilitate the preparation of the next turns. Leading Tones for Turning was also presented to help drivers tune the timing of their turns. We evaluated these new concepts with domain experts in three countries, and improved the details of the functions. We are currently implementing those features and looking forward to demonstrating new displays on the real product in our presentation at the Automotive User Interface conference.