Turn Your Windshield into a Head-Up Display

Q: How does phone HUD mode work?

Tap HUD and the display flips 180°. Lay the phone flat on the dashboard under the windshield, and the glass reflects the mirrored image back right-side-up — your speed appears to float over the road, like a factory head-up display.

Q: Why does it only work well at night?

The reflection needs the screen to be brighter than the scene behind the glass. After dark (or in a dim garage) the readout is crisp; in daylight the sky overpowers it. That's physics for every HUD reflection, not an app limitation.

Q: Is using a HUD legal and safe?

A speed readout you glance at is generally in the same category as your dashboard — but placement rules vary by region, and the phone must not obstruct your view of the road. Put it flat on the dash, not in your sightline, and secure it so it can't slide.

Luxury cars project your speed onto the glass so your eyes never leave the road. The trick behind that feature is a mirror — and a mirror is exactly what your windshield becomes when a bright screen lies beneath it in the dark.

The physics, in one paragraph

Glass at a shallow angle reflects a faint mirror image of whatever's below it. A phone lying flat on the dashboard reflects into the driver's eyeline — but mirrored. So HUD mode pre-flips the display 180°: wrong-way-up on the phone, perfectly readable in the reflection. Bright digits on a black background make the reflection pop while the rest of the screen disappears — which is why the app's dark, high-contrast readout is the right canvas for it.

Setup that works the first time

Wait for dark. Reflections compete with the scene behind the glass; night (or a dim garage for testing) is when the readout floats crisply over the road.
Open the app, tap HUD. The display flips 180° — looks wrong in hand, correct on glass.
Lay the phone flat on the dash, screen up, near the base of the windshield, roughly under your sightline. A grippy mat keeps it planted through corners.
Raise brightness and adjust the phone's position until the digits hover where a glance finds them. Full-screen digital view gives the biggest reflection.
Check your local placement rules — the phone must never obstruct the road view. Flat on the dash, out of the sightline, secured.

When HUD earns its keep

Night highway stretches — speed floating at the horizon beats glancing down, especially in cars whose dials sit low.
Rentals and older cars — instant retrofit for vehicles that never shipped a HUD.
Checking the dashboard's honesty — GPS speed on the glass next to the car's dial makes the comparison effortless.

Daytime alternative: when the sun kills the reflection, skip the flip — the same full-screen digital view standing upright in a dash mount is a perfectly good daylight speed display. HUD is the night shift; the big readout works both shifts.

A HUD for every car

One tap flips the display; your windshield does the rest. Free on iPhone.

Download on the App Store

FAQ

How does phone HUD mode work?

The display flips 180°; the windshield reflects it back right-side-up over the road.

Why does it only work well at night?

The reflection must outshine the scene behind the glass — physics, not the app.

Is using a HUD legal and safe?

Keep the phone flat, out of your sightline, secured — and check local placement rules.