There is an awkward overlap in this hobby. The roads worth driving twice are best driven in something old, and something old does not have a screen. Meanwhile the whole point of a co-driver is that you are not the one reading the book, and a phone propped on the passenger seat is a poor substitute for either.
CarPlay solves it, and getting it into an old car is more straightforward and less invasive than most people expect.
What you actually need
CarPlay is a protocol, not a brand of car. It needs a head unit that speaks it, and that unit does not have to have come from the factory.
A retrofit head unit
The common route. A double-DIN or single-DIN aftermarket unit with wired CarPlay, fitted into the dashboard aperture, driven off the car's existing power and speakers. In a car built between roughly 1970 and 2000 there is usually a standard radio aperture already there, and a fascia adapter for the specific model that makes the new unit sit flush.
Two things to think about before buying:
- Wired or wireless. Wired is cheaper, more reliable, and charges the phone, which matters on a four-hour drive with the screen on. Wireless is tidier and means no cable across the cabin. In an open car, wired.
- Screen size against the dashboard. A large floating screen looks wrong on a wooden dash and will block the view of the instruments you actually need. A modest single-DIN unit with a fold-out or a small fixed screen is usually the better-looking answer, and CarPlay's own layout is designed to work at small sizes.
A wireless CarPlay adapter
If the car already has a factory head unit with wired CarPlay (anything from roughly 2016 onwards), a small dongle plugged into the USB port converts it to wireless. This does nothing for a genuinely old car; it is only useful if the unit is already there.
What you do not need
You do not need to change the loom, remove the original radio permanently, or lose the car's own instruments. Most retrofits are reversible: the original unit goes in a box in the garage and the wiring is a plug-in adapter harness. If the car matters to you, keep the parts.
Getting Roadbook '71 onto the car screen
Once the head unit is in and the phone is connected:
- Open the app on the phone once and grant location access. CarPlay will not show an app that has never been run.
- Reconnect by unplugging and plugging back in, or by restarting the head unit. The CarPlay home screen is built when the session starts.
- If it still is not there, check Settings → General → CarPlay → your car on the phone, where apps can be hidden or reordered.
For guidance to keep running with the phone screen off, set location access to Always. With While Using, iOS suspends the app once it is backgrounded, and the guidance goes with it.
What the car screen shows
The car screen runs the drive itself. It can start one, follow it and end it without the phone, which can stay in a pocket for the whole loop.
Before you set off it draws the whole ring on the car's own map, with the car sitting beside it, and gives you one control. Tapping Go begins the drive at the point on the loop nearest the car rather than at whatever point the recording happened to start from.
Once moving, the maneuver panel carries four things: the instruction you are driving towards, the distance to it, the instruction after that one, and how much of the loop is left. That is the same information a co-driver would give you, in the same order: what is next, how long you have, what comes after, and how far to go.
The route is drawn on the car's map with the part behind you faded and the part ahead at full weight. A stretch where guidance goes quiet is drawn wide and solid so you cannot miss it; a bridged GPS dropout is drawn thin and dashed. Those two look different on purpose, because they mean different things: the first is "you are about to stop hearing instructions", the second is "the instructions here are real but the original recording had a hole in it".
Voice, and not ducking the music
Prompts come through the car speakers, like any CarPlay navigation app.
One design decision worth mentioning, because it is the sort of thing you only notice when it is done badly. Roadbook '71 activates the audio session only while it is actually speaking, and releases it immediately afterwards. Many navigation apps hold the session for the whole drive, which means whatever you are listening to sits permanently ducked, quieter for two hours in case something needs saying.
The trade-off is that a prompt which never arrives is silence rather than a dip in the music. If you are on a stretch with no turn-by-turn, you get nothing at all, which is why the app tells you where those stretches are before you set off.
Day and night
The car screen follows the head unit's own ambient sensor rather than the phone's. This is the correct behaviour and occasionally a surprising one: the phone in your pocket has no idea whether the cabin is dark, and the head unit does. Drive into dusk and the car screen changes on the car's judgement.
What cannot be promised
Two honest caveats.
Retrofit head units vary enormously. They are made by a lot of companies at a lot of price points, and their CarPlay implementations are not identical. Everything described here is standard CarPlay behaviour and should work anywhere, but a cheap unit with a slow processor will feel slow at anything, including this.
And Apple grants the CarPlay navigation entitlement per app, by request. Roadbook '71 was granted it on 1 September 2026, which is what makes the car screen described above possible at all; before that date the app existed but could not appear in a car.