# Vững Lái: Following Distance — Tailgating alerts by phone AI > Tailgating alerts by phone AI (iPhone/iPad app by Dan Duc Vu.) - Source: https://appshunter.io/ios/app/vung-lai-following-distance/id6828459513 (this page in markdown: same URL + `.md`) - Developer: [Dan Duc Vu](https://appshunter.io/developer/6828459515) - Category: Navigation, Utilities - Price: Free - Rating: 5.00/5 from 1 App Store ratings - Age rating: 4+ - Requires: iOS 17.0 · 87 MB - Languages: American English - Released: 2026-11-04 - Data updated: 2026-11-10 ## What is Vững Lái? Vững Lái (Vung Lai) is a following-distance assistant that runs entirely on your iPhone. Mount the phone on the windshield, sideways or upright: the rear camera and on-device AI spot the vehicle ahead in your lane, estimate the distance, compare it with your GPS speed and warn you when you follow too closely. THE 2-SECOND AND 3-SECOND RULE, MEASURED FOR YOU • Canada: the 2-second rule, in km/h and metres. • United States: the 3-second rule, in mph and feet. • Vietnam: Circular 38/2024/TT-BGTVT for dry roads, with a 1-second reminder from 20 km/h below its speeds. • The region is guessed from your phone and can be changed in Settings. ALERTS YOU DON'T HAVE TO LOOK AT • Under the safe distance: the gap card turns amber, and is spoken once it lasts a few seconds. • Really close (under 3/4 of the safe distance): red, sounded at once. • Tones, vibration and voice prompts in English or Vietnamese. • Warning when the gap closes fast: "Careful ahead!". • Stop sign and pedestrian reminders. • Three sensitivity levels: Calm, Balanced, Sensitive. DRIVER ASSISTANCE ON THE PHONE YOU ALREADY HAVE • No extra hardware: a windshield mount is all you need. • Calibrates its camera by itself in the first minutes of driving and remembers the mount. • Scales back its work when the phone gets hot, to keep running smoothly. PRIVACY • Camera images and location are processed on the phone, never recorded or uploaded. • No account, no ads, no tracking. The app collects no data. SAFETY NOTICE Vững Lái is an assistance tool only. It is not a certified measuring device and does not control your vehicle; its estimates can be wrong, especially at night, in rain or fog, against the sun, or with a dirty windshield. The driver is always responsible for watching the road, keeping a safe distance and obeying traffic law. Set the app up before you drive, mount the phone where it does not block your view, and do not operate the phone while moving. Intended for licensed drivers. Requires iOS 17 or later. Support: vudanmax@gmail.com ## Is Vững Lái safe? Not enough ratings yet to assess Vững Lái. ## Is Vững Lái legit? Vững Lái: Following Distance has limited verification signals. The AppsHunter Legitimacy Score for Vững Lái is 58 out of 100 points across 7 verification signals from App Store and developer data. ## Version history (last 2 releases) ### 1.0.1 — 2026-11-07 • Works with the phone upright: the road at the top, the gap large in the middle, buttons at the bottom. • The screen follows how the phone is held, even with the rotation lock on. Take the phone off its mount during a drive and the drive stops and turns with the phone, so swiping out is easy. • If you leave the app during a drive, Vững Lái tells you the warnings are paused. • After a few drives the app may ask for a rating (only when the car is stopped). • Small fixes and stability improvements. ### 1.0.0 — 2026-11-05 No release notes. ## Related topics [auto proximity detection](https://appshunter.io/ios/topics/auto-proximity-detection) --- *Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-11-10.*