PLEASE READ STEPS DOCUMENTATION BEFORE ATTEMPTING AUTHENTICATION. Familarity with Postman is recommended. Postman has encapsulated the OAuth 2.0 sequence reducing the number of steps from the previous release of this collection.
It is not necessary to store your credentials in Postman. Postman presents the Tesla authentication web page from Tesla's website in an embedded browser to generate the access token.
Thanks to Eric Schnabel for the first update that included this method, thanks to Postman for this reference, and thanks to tesla-info for this reference!
Note: This collection does not function as described on the web version of Postman.
USER PREPARATION: Enter the client secret in the environment. This Variable is already defined in the imported "Tesla environment" of Postman. Update the defined "clientsecret" variable which is available here. The client ID is not needed. Save these changes before hitting the button to request a token.
Navigate to the Authorization tab of the "Request Tesla Access Token" call. Scroll to the bottom and click on "Get New Access Token" 
. Postman presents the Tesla authentication web page from the Tesla website. Enter your credentials. If MFA is enabled, it will request a code.
The Tesla Log In Sequence collects your email, password, and MFA code (if enabled).
When the authtication completes, the access token and refresh token are placed into the Token Manager 
and named with the most recent date and time 
.
To use the tokens, they must be copied and pasted into the environment. Presently, this is a manual task; Postman may provide some automation in the future. Carefully copy the access token to the access_token environment variable, and copy the refresh token to the refresh_token environment variable.
Note the access token is valid for eight hours.
The purpose of this step is refresh the access token, update the requestState environment variable, and to initialize an environment variable that contains the expiration date and time (readableValidUntilDate). The value of readableValidUntilDate is presented in the Console to show the expiration date and time of the access token. You DO NOT have to wait for an access token to expire before using Refresh Tesla Access Token.
Click on Send to refresh the access token. Note that the refresh token is valid for 60 days. After the refresh token expires, it is necessary to use Request Tesla Access Token to create valid access and refresh tokens (I have not validated the 60 day claim).
NOTE: Use Get Vehicles first.
The Get Vehicles call retrieves a list of vehicles on your Tesla account. It extracts the id_s variable for the first vehicle and stores it in the teslaVehicleIdS environment variable. Without this value, other API calls will fail. Once id_s has been retrieved, Get Vehicles is not needed for the API calls.
The Wake Vehicle call wakes a sleeping vehicle. A vehicle must be online to respond to requests for vehicle information.
The Tests contains a check named Vehicle On-Line Check. If the test passes, the vehicle is online. The access token expiration date and time appear in the Console.
The Get Vehicle Data call retrieves all available data for the vehicle defined by the teslaVehicleIdS environment variable.
The Get Drive State call retrieves drive state data (location, power, shift state, and other data) for the vehicle defined by the teslaVehicleIdS environment variable.
The Get Charge State call retrieves charge state data (battery level, charging information, and other data) for the vehicle defined by the teslaVehicleIdS environment variable.