Currently broken by Tesla

It would seem Tesla is no longer accepting fleetkey.cc domains. I have raised a support request.

Your unique origin domain is https://ac9f8.fleetkey.cc

Do this first (Step 3)

A public key must be hosted on the application's domain before making calls to Fleet API. The key is used to validate ownership of the domain and provide additional security when using Vehicle Commands and Fleet Telemetry.

First generate a private key. This needs to be placed in your Home Assistant config directory for command signing.
openssl ecparam -name prime256v1 -genkey -noout -out tesla_fleet.key

Then generate a public key. This needs to be pasted below.
openssl ec -in tesla_fleet.key -pubout -out public_key.pem

Application (Step 2)

Create a Tesla Fleet application and set its origin to https://ac9f8.fleetkey.cc, and redirect to https://my.home-assistant.io/redirect/oauth.

Create Fleet API application

Registration (Step 4)

Generate a partner authentication token and use it to call the register endpoint to complete registration with Fleet API. You can run these commands manually if you prefer, however these details are not stored.

Client ID

Client Secret

Setup integration in Home Assistant

Now you're ready to add the integration and authorise your account with OAuth.

Add integrationt to Home Assistant

Add Virtual key to vehicles

After you have setup the integration in Home Assistant, you can install your virtual key with the Tesla App by scanning or touching the QR code.

Is this too hard or confusing?

Teslemetry is the easy way to get real-time data into Home Assistant. Click here to check it out.