> ## Documentation Index
> Fetch the complete documentation index at: https://docs.axle.energy/llms.txt
> Use this file to discover all available pages before exploring further.

# Cars

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  <img src="https://mintcdn.com/fascinating-teal-alpaca/cPhc5V0fQ2Bi75Qi/images/cars.svg?fit=max&auto=format&n=cPhc5V0fQ2Bi75Qi&q=85&s=6ada15ee95e7abd341ed8d57a4bbd72f" alt="ev-chargers" width="732" height="292" data-path="images/cars.svg" />
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Axle integrates directly with electric vehicles via your API, enabling smart charging control without requiring a connection to your charger.

Your customers can participate in flexibility programmes regardless of which charger they use at home.

## Smart charging principles

We always prioritise the customer's needs when optimising car charging.

Our optimisation satisfies the following constraints, in order:

1. Ensuring the customer's desired State of Charge (SOC) is met
2. Minimising customer's bills
3. Maximising flexibility revenue

## Customer propositions

### The "free miles" proposition

Car integrations are particularly well-suited to **free miles** propositions — where Axle pays the customer per kWh charged, offsetting their electricity costs. The cost of charging is calculated at a flat fee per kWh (e.g. 8p/kWh), and is paid by Axle to the customer's bank account.

1. Customers opt-in to smart charging, delivered via your app
2. Axle schedules charging via a backend integration, ensuring customer's needs are met whilst maximising flexibility value.
3. Axle pays customers per kWh of charging, offsetting their electricity costs.

### Custom propositions

Axle's flexible payment rails allow you to build custom propositions for your customers, mixing up-front and recurring payments. See [paying users](/workflows/ev-charging/paying-users).

## Geofencing

Axle only controls charging when the vehicle is at home. To determine this, we use a **"car is home" signal from your API** — we do not require location or GPS data, only a boolean indicating whether the car is at home.

In practice, this often means:

* Your API sends plug-in events to Axle only when the car is at home
* Plug-in events at public or workplace chargers should not be forwarded to Axle

Axle treats every plug-in event it receives as a home charge, so the simplest implementation is to filter at source.

## Next steps

Choose your EV flexibility solution and start planning your integration [here](/workflows/ev-charging/overview).