Vehicle intelligence
Everything below is how Stallion actually behaves today. Where a feature has a limit, the limit is stated rather than left for you to discover on a drive.
01Getting connected
Usually under the dashboard on the driver's side, near the steering column. Plug in your adapter, turn the ignition to "on" (the engine can be off), then scan.
Every petrol or diesel car sold in the US since 1996, and in the EU since 2001 (petrol) or 2004 (diesel), has one. It is a trapezoid with 16 pins.
Any ELM327 adapter works. Prefer a Bluetooth Low Energy model — the cheapest clones drop the connection mid-drive and lose the trip.
On iPhone, avoid Wi-Fi-only adapters: Stallion talks to adapters over Bluetooth, and iOS does not expose Classic Bluetooth serial to apps, so a Classic-only dongle cannot work either. On Android both Classic and BLE adapters are usable.
Almost always one of these, in this order:
Cheap ELM327 clones are the usual cause; they overheat or reset under sustained polling. A known-good BLE adapter is the fix.
Stallion reconnects on its own when the adapter comes back, and a trip that was recording resumes rather than starting a second one. Distance covered while disconnected is not recovered, because the app never saw it.
Turn on Always-record on the connect screen and Stallion remembers the adapter, re-connects when you open the app, and starts trips on its own from there.
It cannot reconnect from fully closed — iOS and Android do not let an app wake itself for a Bluetooth accessory it merely likes. Open Stallion once at the start of a driving day and it handles the rest.
The adapter reports the vehicle's VIN, and Stallion binds it to the car you connected under. If you move the adapter to a second car, the VIN no longer matches and you get a banner instead of silence.
That is deliberate: filing one car's trips and fuel against another is the kind of error that is invisible for months and unfixable afterwards.
02On the road
To keep logging your route and fuel use after your phone locks. Without it a trip stops the moment you put the phone down.
It runs only while a trip is recording, your device shows its own indicator the whole time, and you can decline it — you then get trips only while the app is open and on screen. Background recording uses more battery than normal.
It depends on what your car reports. Stallion tries the engine's own fuel-rate reading first, then estimates from the mass-airflow sensor, then from manifold pressure, and shows a confidence band per trip saying which one it used.
The manifold-pressure path needs your engine displacement. Without it the estimate assumes 2.0 litres and reads roughly 43% low on a 3.5-litre engine. Displacement comes from the VIN decode when you add the car, so entering a VIN is worth the thirty seconds.
Trip averages are a harmonic mean, which is the arithmetically correct way to average a rate over distance. A drive that runs 20 mpg for half the distance and 40 mpg for the other half averages 26.7 mpg, not 30.
The simple average is the flattering one, and it is wrong: it would tell you the tank lasts longer than it does.
No. Trips exist only while an adapter is connected, because the engine data is the point — GPS alone gives distance but not fuel.
You can always log distance by updating the odometer, and log fuel as a fill-up, without any hardware at all.
03What it costs
A finished OBD trip writes a companion entry valuing the fuel it burned, so efficiency has something to work from between fill-ups.
It is consumption, not a purchase, and it is excluded from every money total — only fill-ups you logged count as spend. Efficiency deliberately uses both.
No, but the numbers are only as complete as what you log. Stallion treats its records as a sample rather than a ledger: distance, fuel and spend totals are minimums, and a gap means "not logged", never "did not happen".
The AI features are told this explicitly, which is why they will not scold you for an unlogged month.
Yes — miles or kilometres, mpg (US or imperial) or L/100 km, and your own currency, all in Account settings. Every input field is labelled in the unit you picked.
Distances are stored internally in kilometres and converted for display, so switching units never rewrites or rounds your history.
From what you enter. Stallion can suggest a price from your own history, and in the US it can pull regional averages, but the figure on a fill-up is always the one you confirm.
04Staying ahead
Set them by date, by mileage, or both, and Stallion notifies you when either comes due. Mileage reminders track against the odometer you keep updated — manually, or automatically from OBD trips.
Notifications need permission at the OS level. If you declined it, reminders still appear in the app but nothing will interrupt you.
If your car has a VIN, Stallion checks the NHTSA safety-recall database weekly and shows anything open. Each one is presented twice: a plain-English summary beside the verbatim campaign text from the manufacturer.
It is US data. Always confirm with your dealer before acting — the app links straight to nhtsa.gov so you can look up the VIN yourself.
Trim comes from the VIN or not at all. Year, make and model cannot separate a Challenger SXT from an R/T Scat Pack, and the two share neither service intervals, fluids, tyres nor costs — so Stallion leaves it blank rather than guessing.
Add the VIN in the car's details and the decode fills it in. A later save without a VIN will never wipe what a decode established.
05More than one
A group of vehicles — home, work, or a fleet. New cars land in whichever garage you have selected, and you can move a car between garages at any time.
Your default garage cannot be deleted; deleting any other garage moves its cars there rather than removing them.
Yes. Share a vehicle and the people you invite see its logs and can add their own, with changes syncing to everyone.
Leaving a shared vehicle removes your local access only. The owner keeps all the data.
06Your account
Yes. Everything is written to your device first and queued for sync, so the app is fully usable with no signal — logging a fill-up at a pump in a basement garage works exactly as it does at home.
When you come back online the queue pushes and then pulls anything changed elsewhere. Signing in on a new device runs a full historical pull.
Yes, with any authenticator app (TOTP) — Account → Privacy & Security. You will be asked for a code on each new sign-in.
Keep your recovery method safe. Losing both the authenticator and the recovery path means losing access to the account.
English, Turkish, Spanish, French, German, Arabic, Portuguese and Chinese, with full right-to-left layout in Arabic. It follows your device language by default and can be set explicitly in Account settings.
Maintenance and fuel history export from their own screens, and reports generate as PDFs you can share or print from the system share sheet.
From Account settings. Deletion removes your synced data; anything already exported to your own files stays yours. If you want confirmation in writing, email support@thestallionapp.com.
07What we do not do
Your vehicle details, logs and — when the data is good enough to be worth using — recent engine readings. It is told the current date, how long you have owned the car, how long you have been tracking it, and where the gaps are.
Your VIN, licence plate and GPS coordinates are deliberately withheld. No location data reaches the AI provider.
It is built to withhold rather than invent: there are no minimum output counts anywhere, an empty recommendation list is a valid answer, and a brand-new car gets a fixed "nothing due yet" plan with no model call at all.
Treat it as a well-briefed second opinion, not a mechanic. It reads your logs; it cannot hear your engine.
No. Stallion contains no advertising or third-party tracking SDKs, uses no advertising identifiers, and does not sell personal data.
The full privacy policy is at thestallionapp.com/privacy.
If the answer is not here, it should be. Tell us what you were trying to do and we will write it down.