A HUD speedometer app for iPhone

See the difference

Readable on the phone, reversed for the glass

Use HUD without Mirror when looking directly at the phone. Turn on Mirror for a windshield reflection: the speed readout reverses on the phone so its reflection can read normally.

Illustrated comparison: the left is a crop from a saved app screen with sample values. The right reverses that crop to explain Mirror. It is not a new capture or a photograph of a windshield, and it does not demonstrate GPS accuracy or reflection quality. App controls are outside the crop.

1. While parked, tap HUD, then Mirror.
2. Secure the phone and check the reflection without changing your normal driving posture.
3. If the reflection is faint, doubled or distracting, use Normal with a suitable mount instead. Do not adjust the phone while moving.

Read the full HUD setup and limits · Compare with navigation-app speed displays

What HUD mode shows

• Large green speed digits on a black background, with the unit
• GPS status
• Trip distance, max, and average in small tiles
• Buttons: Pause/Resume, Normal, Mirror, Settings

How a phone HUD works

A phone lying flat on the dashboard reflects in the windshield like a dim mirror. Because reflections reverse the image, the app flips the display horizontally so the numbers read the right way round. It is the same idea as dedicated HUD gadgets, using the screen you already have.

When it works well — and when it doesn't

• Best at dusk and night, when the reflection has contrast.
• Weak in bright sun; the reflection washes out. Use the normal display, mounted, instead.
• Steep, laminated, or coated windshields can create a double image.
• The phone must lie securely — a non-slip dash mat or mount — and never slide or block vents, airbags, or your view.

For setup steps, read using HUD mode safely.