Z-Maps Car
Guide
Four steps for your first run, and what each Settings option actually does.
First run
Four steps to a speed warning you can trust
Grant location permission
Without it the app can measure nothing. If you declined by accident, go to Android Settings → Apps → Z-Maps Car → Permissions and turn it back on.
Wait for 'GPS good' before driving
The first fix can take a minute or two, especially just after the unit powers up. Parking with a clear view of the sky makes it faster.
Check which speed source is in use
If the app shows 'speed computed from GPS', your unit's GPS module is reporting speed incorrectly and the app has switched to deriving it. That is a normal state on many head units, not a fault.
Set a safety margin that suits you
It defaults to +5 km/h. Lower it if you want earlier warnings, but do not set zero — GPS is a few km/h out and the app would cry wolf constantly.
What each Settings option actually does
Settings has four groups. Here is what each one means in practice, and when it is worth changing.
Alerts
- Safety margin — nothing counts as a violation until you exceed the limit plus this much. Default +5 km/h.
- Voice alerts — turn it off to leave only the beep. If the device has no Vietnamese voice, the app falls back to the beep even with this on.
Speed limits
- Estimate when data is missing — on, the app infers a limit from road class under Circular 31/2019 wherever the map has none. Off, those stretches raise no alert at all.
Map
- Map style — Liberty for full detail, Dark for night driving, Positron for a paler, quieter screen.
- Always north-up — off means the map turns with the car, which is the default.
- Keep the screen on — for head units that blank the display mid-journey.
Directly under this group is a button that clears every limit you have corrected by hand, returning the app to map data and its estimates.
Trips
Open the trip history from here: total trips, total distance and total time, then each journey with its average speed, maximum and overspeed count. Delete a single trip or all of them. Journeys under 300 m are not recorded.
Map cache
The app stores up to 512 MB of the roads you have driven, so they survive losing signal. The clear button is at the bottom of Settings, for when storage is getting tight.
Correcting the limit on a stretch of road
When the app reports the wrong limit, open the limit editor from the driving screen. Pick the correct figure and the app remembers it for the area around that position, using it again next time. 'Use the default again' undoes it. You need a GPS fix, and the app must have identified the road you are on, before it can save one.
Alerts keep running when the app is not on screen
The driving loop lives in a foreground service, not in the screen. Select reverse and let the camera take over the display, or take a call, and the trip and the speed alerts carry on — the 'Z-Maps Car is running' notification is how you know the service is alive.