Fleet Telemetry on Legacy Vehicles

With firmware 2025.20, Fleet Telemetry has finally arrived for legacy Model S and Model X vehicles with MCU2.

This is a massive development for owners of pre-2021 Model S and Model X vehicles, as it brings the modern streaming data capabilities that have been exclusive to newer vehicles since 2023. More importantly, this arrives just in time for Teslemetry's transition away from vehicle data polling on July 1st.

Perfect Timing

When we announced the road away from vehicle polling in March, it was still unclear if these features would ever come to legacy vehicles. Since 2023 modern vehicles have streamed their telemetry in realtime directly to Teslemetry, and now with this new firmware release, most legacy vehicles can also enjoy the same benefits.

What You Need

To enable Fleet Telemetry on your legacy Model S or Model X, you'll need:

• MCU2: Vehicles with the original MCU1 are not supported
• Firmware 2025.20 or newer: This is the minimum version that includes Fleet Telemetry support
• Settings configuration: Unlike modern vehicles, no virtual key installation is required

Enabling Data Streaming

The setup process is refreshingly simple compared to modern vehicles. There's no virtual key to install or complex authentication flow to complete. Simply navigate to:

Settings > Safety > Allow Third-Party App Data Streaming

Once enabled, your legacy vehicle will immediately begin streaming its configured telemetry data to Teslemetry, providing real-time updates without the need for polling.

Benefits Over Polling

Fleet Telemetry brings several advantages over the traditional polling approach:

• Real-time updates: Data streams continuously instead of being fetched on an interval
• Cost efficiency: No more expensive vehicle_data API calls
• Better battery management: Streaming doesn't wake the vehicle like polling does
• Richer data: Access to additional fields not available through the REST API

Preparing for July 1st

Legacy vehicle owners should update to firmware 2025.20 and enable data streaming as soon as possible. While there are currently no planned changes to legacy vehicle polling on July 1st, having Fleet Telemetry enabled ensures you're ready for any future transitions.

For Home Assistant users, the integration will be updated to correctly identify when your vehicle supports Fleet Telemetry and seamlessly transition to streaming data, providing an even better experience than the current polling-based approach. There are some nuanced differences in the entities provided by polling and streaming.

The Future

We are pleased to see Tesla is slowly bringing Fleet Telemetry to their older vehicles, allowing them to enjoy the same efficient, real-time data streaming that modern vehicle owners have had access to for over a year. Welcome back, to the future.