NitroHUD is an offline GPS speedometer and windshield head-up display (HUD) for Android. Free features: large GPS speedometer with the current GPS accuracy shown next to the reading, km/h and mph units, HUD mirror mode that flips the readout so it reflects readably on the windshield at night, compass heading derived from the GPS track, a live trip readout (distance, duration, average and top speed), one user-defined over-speed alert (beep and on-screen warning), and keep-screen-on while driving. PRO subscription features: 12 extra gauge designs (15 total: analog needle, digital seven-segment, LED bar, aviation tape, thin ring, arc), 4 extra dashboard layouts including a quad cockpit, a GPS-timed acceleration timer (0-50 km/h, 0-100 km/h, 0-60 mph, 60-100 km/h, 0-100 m, 0-400 m) with saved personal records, a G-force meter using the device accelerometer with peak hold and a calibration control, unlimited saved trip history with a speed graph, CSV and GPX export of a trip, altitude and road-grade readout, persistent total and A/B trip odometers, a screen brightness boost, a custom accent colour and multiple speed alerts. Monetization: auto-renewing subscriptions sold through Google Play Billing in weekly, monthly and yearly plans, each with a 3-day free trial. There are no ads and no ad SDK. There are no user accounts, no sign-in and no cloud sync. Permissions used: ACCESS_FINE_LOCATION and ACCESS_COARSE_LOCATION, requested only while the app is in the foreground, used solely to compute speed, distance, heading and altitude on the device; the app declares no background-location permission and runs no foreground service, so location tracking stops when the app is not in the foreground. INTERNET is present because Google Play Billing requires it and the app fetches a small remote configuration file. A demo mode can simulate a drive for users who want to see the gauges without driving; it is clearly labelled as simulated.