Questions
How accurate is a GPS speedometer?
With a clear view of the sky, phone GPS speed is usually within 1 to 2 km/h of your real speed. It gets worse in tunnels, between tall buildings and indoors.
Why does my car show a higher speed than GPS?
Car speedometers may read high but never low, so most show a few percent more than your real speed. GPS measures your actual speed over the ground.
Does it work without mobile data?
Yes, once the page has loaded. GPS needs no data connection, though the first fix can take longer without it. The screen stays on while the speedometer runs.
What is the HUD view?
A full screen view with large digits. Turn on Mirror and lay the phone under the windshield, so the reflection reads the right way at night.