An old phone on the windscreen
Most people install a map app and stop. The interesting part is what an old phone can do once it is mounted permanently: a dashcam that loops, an engine diagnostic reader over a cheap adapter, a fuel and service log that outlives the car, and a parking app for the city you visit twice a year. None of it needs a new phone.
Set it up in the driveway, not at the lights
| Job in the car | What does it | What it needs from you |
|---|---|---|
| Navigation | A map app, ideally with the maps downloaded | Set the destination before moving off |
| Interface on the car screen | Android Auto, wired or wireless | A compatible head unit |
| Dashcam | An old phone, mounted and powered | A card with space and loop recording on |
| Engine warning lights | An adapter plus a diagnostic app | A cheap adapter and a minute parked |
| Fuel and servicing history | A logging app | Thirty seconds at each fill |
| Parking in an unfamiliar city | A parking app that covers that country | Checking coverage before you travel |
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The apps
Android Auto. Puts maps, messages and audio on the car's own screen with a driving safe interface. The first thing to try if the car supports it.
Best in heavy traffic and for hazards reported by other drivers. Online only, which is worth remembering on a rural route.
Proper offline turn by turn, downloaded per country. The one to have for driving abroad without roaming.
Offline navigation with strong voice guidance. Core navigation works with no connection, and the extras are paid.
The strongest option across Russia and neighbouring countries, where its traffic data is far better than the global apps.
Warns about speed cameras and limits. Legality of camera warnings varies by country, so check before relying on it abroad.
Parking locations and prices, with better coverage in some countries than others. Check your city before a trip rather than at the barrier.
Turns a spare phone into a loop recording dashcam, with speed and location stamped on the video.
Car Scanner. Reads engine codes and live data through an inexpensive adapter, and explains what a warning light actually means.
Torque Lite. The long standing alternative for the same job, with a dashboard of live readings.
inCarDoc. Another diagnostic reader, useful when one app does not get on with your particular adapter.
Carly. Deeper diagnostics on supported makes, with its own adapter. Read what it supports for your model before spending anything.
Fuelio. A fuel and expense log with consumption over time, which is how you notice a car quietly getting thirstier.
Drivvo. The same idea with a stronger servicing and reminder side, for anyone keeping a car past its warranty.
Sort the offline playlist out before a long drive. Streaming through a tunnel or a valley is the most predictable failure in a car.
The alternative for long distances, and it downloads episodes over WiFi so the drive costs no data at all.
Making an old phone into a dashcam that works
- Mount it low and out of your sightline Windscreen mount rules differ by country, and a phone in the wrong place is both illegal and unsafe.
- Power it permanently A dashcam app records for hours, so it needs a cable from a socket that only powers up with the ignition.
- Turn on loop recording and set a file length Short files that overwrite themselves are the whole point. Without it the storage fills and recording stops.
- Watch the heat A phone on a windscreen in direct sun will throttle or shut down. Park it in shade, take the case off, and do not expect it to survive a summer afternoon on the dashboard.
- Export the clip you need the same day Loop recording deletes evidence on schedule. Anything that matters has to be moved out of the loop folder immediately.
- Occasional recording on known routes
- Trying the idea before buying hardware
- Location and speed stamped on the file
- A second camera facing the cabin
- Surviving heat and cold on a windscreen
- Starting and stopping with the ignition
- Parking mode while the car is unattended
- Night footage, where the optics matter
Set it all up parked. An old phone, a mount, a permanent cable and loop recording turns a spare handset into the most useful thing in the car.
Frequently asked questions
Do I need a special adapter to read engine codes?
Yes, a Bluetooth or WiFi diagnostic adapter that plugs into the car's port. They are inexpensive, quality varies, and some apps get on with some adapters better than others.
Will a phone dashcam drain the car battery?
Not if it is on a socket that switches off with the ignition. A permanently live socket plus a phone recording all night is exactly how a car battery gets flattened.
Is Android Auto needed for any of this?
No. It is a nicer interface for navigation and audio when the car supports it. Everything else here works from a mounted phone on its own.
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