As we near the winter months and temperature begins to drop across various parts of the world, Tesla owners living within cold climates will inevitably resort to their vehicle’s onboard climate control settings and seat heaters to stay warm. But understanding how much power each component consumes could mean the difference between going that extra mile, especially when driving in snowy conditions could rob upwards of 25% in range, and being stuck at a Supercharger longer than need be.

We take a look at the most optimal way to stay warm in your Tesla this winter, thanks in large part to the help of YouTuber and Model S owner, KmanAuto. He takes us an inside look on the amount of power Tesla’s SubZero Weather Package, and its heating and air conditioning (HVAC) system, consumes.

First, it’s worth noting that Tesla’s SubZero Weather Package is an optional add-on that includes the addition of seat heaters throughout the cabin, heated wiper blades, heated washer nozzles, and a heated steering wheel which Tesla later added into the package.

Using a third-party app called Remote S, KmanAuto measures the amount of current draw and power consumed by each feature within Tesla’s Subzero package. He then undergoes a series of tests combining seat heaters with the HVAC heater at different fan speeds and notes power consumption with each combination. At one point, Kman turns on the heater to ‘HI’ (82F) – commonly used by owners when first entering a frigid car – and measures a staggering 16.8A, 6.4kW of power consumed, or 18+ miles of range lost per hour. Though running the heater at HI for an hour is an unlikely scenario, especially considering the fact that the cabin temperature quickly reached 108 degrees Fahrenheit (42C) within a short amount of time, Kman brings to light that quickly warming up a vehicle using the heater could have significant and detrimental effects on range.

Instead, it’s advised to use seat heaters as the primary source for warming oneself up, combined with a slow warming of the in-cabin air by setting it to room temperature.

Tesla Subzero Weather Package + HVAC Energy Consumption

Energy consumption has been broken down by feature. Total energy consumption can be added together based on the number of features that are enabled.

Assuming a consumption of 333Wh/mile, we can compute the approximate range loss at miles per hour (mph) as a result of having these heating features on.