Help and frequently asked questions

• High and near the middle of the windshield: below or beside the rear-view mirror stem, offset toward the passenger seat, without blocking your view.
• Inside the area the wipers sweep, so the camera can still see the road when it rains.
• Clamp it to the glass or the mirror stem, not to the mirror itself. Choose a mount with a short arm (under about 10 cm) to reduce shaking.
• Hold the phone in landscape; make sure the clamp doesn't cover the rear camera lens.
• At night, lay a matte black mat on the dashboard to cut glare reflected onto the windshield.

The app has a Mount assistant to check the phone's position and angle before you drive.

Yes, if you know it. It's the distance from the lens down to the road; a phone mounted at the driver's eye level in a passenger car is usually about 1.2 m. The closer the number is to reality, the steadier the distance estimate.

When you drive on a straight road with clear lane markings, the app learns the phone's mounting angle by itself. The screen shows “Self-calibrating …%”. Just drive normally for a few minutes until it finishes. The result is saved for later trips.

The mount has shifted since last time. When the car is safely stopped, check the clamp, then keep driving; the app will recalibrate by itself. If you switch to another car or change where the phone is mounted, run the Mount assistant again.

Check that the windshield is clean, the lens isn't blocked, the phone is level and secure, the camera height is correct, and calibration has finished. At long range, in the dark, in the rain or on curves, the error will be larger. This is an assistance tool, not a measuring device; always watch the road yourself and keep your distance.

Camera is used to see the road ahead; images are processed right on the phone, never stored and never sent anywhere. Location is used only while the app is open, to get your speed from GPS and pick the matching safe distance. See the Privacy Policy for details.

Go to Android Settings → Apps → Vững Lái → Permissions, and turn on Camera and Location (choose “Allow only while using the app” and turn on “Use precise location”). Then reopen the app.

The app still recognizes the car ahead but can't compare the gap with the speed-based distance. Turn on the phone's Location, let the phone see the sky through the windshield, and wait a few dozen seconds after starting.

Vững Lái speaks in the app language (Settings → Language). If the phone has no voice for that language:

1. In Vững Lái's Settings, tap DOWNLOAD VOICE. It opens the phone's speech-engine download screen. You can also go to Android Settings → System → Languages → Text-to-speech output (the menu names may differ by phone brand).
2. Pick the Speech Services by Google engine. If the phone doesn't have it, install it from Google Play.
3. Tap the gear icon → Install voice data → choose the app language (English or Vietnamese) → download (needs an internet connection, a few dozen MB).
4. Go back to Vững Lái and tap TEST ALERT.

Until a voice is installed, the app still warns you with alert tones and vibration.

Tap VOLUME in the app's Settings, check that the phone isn't on silent or Do Not Disturb, and if the phone is connected to the car over Bluetooth, check the car's volume. You can choose a voice style: Standard, Friendly, Cheerful, or Custom to write your own reminder phrases.

The camera and AI run continuously, so the phone will get warm. When it gets too hot, the app automatically cuts back on processing to protect the phone, so alerts may come later. To limit heat:

• Keep the phone out of direct sunlight; turn on the air conditioning and point a cool vent toward the phone if you can.
• Charge with a regular cable; avoid fast charging and wireless charging mounts, because charging heats the phone considerably.
• Remove a thick case; close other heavy apps that are running.
• If the phone is too hot, stop the car in a safe place and let the phone rest.

Yes. When you switch to Google Maps, Vững Lái shrinks into a floating window (picture-in-picture) and keeps warning you. If the floating window doesn't appear, go to Android Settings → Apps → Vững Lái and turn on the Picture-in-picture permission.

By default the app uses the table from Circular 38/2024/TT-BGTVT (Vietnam). In Settings → Gap rule, you can choose a time-based rule (BY SECONDS, for example the 2-second rule) or set up your own table (CUSTOM TABLE).

Go to Android Settings → Apps → Vững Lái → Storage → Clear data (“Clear storage” on some phones), or uninstall the app. Your data lives only on your phone, so it is deleted for good.

On the Trips screen, choose to share the logs, then email them to us. The logs contain only technical readings, with no images and no location. You can turn on “Keep logs to improve the app” in Settings to make the logs more detailed.