Toyota Prius Prime Navigation

The map and navigation system in our new 2017 Toyota Prius Prime is, in a word, disappointing.

Example 1: Going to a favorite mountain destination the navigation system successively directs me to:

  • Drive up a narrow hiking trail that has never been open to motorized vehicles
  • Go up a section of four wheel drive road that has been closed for at least 50 years and restored to a natural state.
  • Take a turn on to a “road” that has never existed.
  • And finally, complete the trip going up what once was a four wheel drive road but has been closed to motor vehicle traffic for over 25 years.

Example 2: Even though the OpenStreetMap edit history showing a new section of freeway on California Highway 58 was opened six months before our car was purchased, the navigation system tries to route you over the old two lane road.

In my old Prius, the display defaulted to a hybrid status display and I could simply use a dash mount for my phone for navigation and ignore the ancient map data on the car’s navigation system’s read only DVD.

I really want the built in navigation in the new Prius Prime to work better:

  • The huge vertical display in the new Prius Prime defaults to maps and navigation so it is not as easy to ignore a bad map as it was in my old car.
  • The GPS/navigation system appears to integrate data from the tires and steering into its position estimation and seems to be more precise than my phone’s GPS so with a good map it should provide a better experience than my phone or a tablet.
  • The car’s navigation system can get traffic data from HD radio and use it to route based on congestion. My phone can only do that if I enable mobile data.
  • I would rather not clutter up the dash with a phone mount and cables, especially as there is a nice Qi wireless charging tray to hold the phone.
  • It would really be nice to have free and timely OpenStreetMap based updates to the car’s navigation system like I have for my phone.


Apparently Toyota’s newest Entune® 3.0, only available on a few 2018 models, changes out everything for a system originally developed by Ford. Smart Device Link (SDL) has Android libraries available so writing a OpenStreetMap based offline navigation app should be possible. Unfortunately, my new car has the older Entune® system so this is not an option.

Per the owner’s manual and various online chat forums, map updates for my car are installed by putting a microSD card into a slot under the bezel of the display.

According to a government website, in the United States Toyota apparently uses data from Here Maps.  This seems to be true as the frightfully incorrect road network shown on Here Maps for my favorite mountain matched what I saw in the car. It was so egregiously wrong that I created an account and corrected that area. I have no clue how long it will take to have my fixes propagate into Toyota’s map distributions. And I don’t like having the results of my free labor become someone else’s intellectual property that I have to pay to use.

Based on some chat forums, Toyota releases new map data once a year. For the ridiculously high cost of $300 you can have your car’s maps updated. Basically the same cost you can buy two or three low to middle range Android phones and run OsmAnd or and have free map updates every month forever. Apparently you can get Toyota map update microSD cards from Amazon for considerably cheaper than from the dealer. But cheaper is still more expensive than a free OpenStreetMap based update.

Apparently in some other parts of the world Toyota uses data from Garmin. The instruction for updating maps there include:

  • Putting a blank 4GB microSD card into the slot for the car to do some magic on it.
  • Move the microSD card to a computer and running some Garmin software to put maps on it.
  • Move the microSD card back to the car to actually update the maps.

For at least some years, there are several suppliers of the Prius navigation system so it is not clear if the microSD card format and data are the same all around the world.

I’ve not been able to find an open source project that is creating maps for Toyota and/or KIWI-W navigation systems.

The 2004-2008 “Gen 2” Toyota Prius maps were distributed on ISO formatted DVDs that contained of a bunch of .kwi files. These appear to be based on an open specification from the KIWI W Organization. See also

The general look and feel of the navigation system is remarkably similar to the one in the old “Gen 2” Prius. Is it possible that the 2017 Prius Prime also uses KIWI formatted data in its navigation system?

Things To Do

  • Verify that a microSD card isn’t already in the car’s slot. Some sites indicate that the card should always be there. There appears to be no card in the slot. But it is a very hard location to actually see, so I could be wrong. Nothing feels to be in it either.
  • If need be, acquire a blank 4GB microSD card and see if the car formats and or writes anything on it when inserted in slot.
  • If need be, acquire a map update microSD card image.
  • Examine the format and content of an official Toyota map microSD card to determine if the map files are in an openly documented format. Or if not documented, easily reverse engineered.
  • Continue search for open source project(s) that create Toyota (possibly KIWI) map files from OpenStreetMap data.

Worse case scenario will be to create FOSS new project to build map microSD volume image from OpenStreetMap data. But that seems like a pretty big undertaking. It would be a lot easier to not have to start from scratch.

Edit/Update: Accessing information on the map that came with the car indicates that it dated 2017-04-01 and the copyright on the map data by Here Maps. Map version is listed as 05-37-51.