The OBD2 Bluetooth dongle
Roadbook Studio measures distance from your car’s gearbox — read live over a small plug-in adapter — not from GPS. That is what makes the trip meter, pacenote calls and roadbook triggering accurate enough to rally with. The adapter is the one piece of hardware you need.
Distance from the car, not the sky
GPS drifts, drops out under tree cover and in valleys, and updates too slowly to place a call or a tulip precisely. Your car already counts distance perfectly through its gearbox — the app reads that speed many times a second and adds it up, the same way a rally trip meter does. One quick calibration over a known distance and the odometer matches the road. Everything distance-driven depends on the dongle; only viewing and sharing PDFs works without one.
- ✅ Bluetooth Low Energy (BLE)
- ✅ ELM327-compatible chipset
- ✅ Standard 16-pin OBD2 port
- ✕ Wi-Fi adapters (won’t pair with iPhone)
- ✕ Classic Bluetooth / SPP adapters
Requirements
The app connects over BLE — the modern low-power Bluetooth iPhones use. Avoid Wi-Fi adapters (they don’t work with iOS) and older classic Bluetooth / SPP adapters.
An ELM327 chipset (or a faithful clone) that speaks the standard AT command set and returns live vehicle speed (OBD2 mode 01, PID 0D). Most generic “OBD2 BLE” adapters qualify; quality of clones varies.
The 16-pin OBD2 socket fitted to essentially all road cars (petrol from ~2001, diesel from ~2006 in Australia). Competition cars vary — if the car reports speed on OBD2, the app can read it.
The app is iPhone-first today. Any BLE OBD2 adapter that pairs with iOS will work; a good one streams speed several times a second for smooth distance.
Three steps
- 01Plug in
Push the adapter into the car’s OBD2 port (usually under the dash, near the steering column). Turn the ignition on.
- 02Connect
Open the app, tap Connect, and pick the adapter. It pairs over Bluetooth — no cables, no account needed to start.
- 03Calibrate
Drive a known distance once and enter it. The app locks the odometer to your car so every stage measures true.
Recommended adapters — coming soon
We’re finalising a supported adapter and bundle options so you can buy a known-good dongle with your subscription and skip the guesswork. In the meantime, any adapter meeting the requirements above will work.
Ask about adaptersReady to record a course?
See what the free capture app does, then create an account and pair your dongle.
About the app