You generally only need to let a modern car idle for about 30 seconds to 1 minute in winter before gently driving away, even on very cold days.

Ideal warm‑up time

  • For most fuel‑injected cars (late 1980s and newer), 30–60 seconds of idling is enough to circulate oil through the engine.
  • After that, the fastest and safest way to warm the engine is to drive gently rather than letting it sit and idle.
  • In very cold climates (well below freezing), you might extend idling to about 2–3 minutes mainly for comfort and defogging, not because the engine needs it.

Older cars and extreme cold

  • Older vehicles with carburetors may need a bit longer, often around 2–5 minutes, to run smoothly and avoid stalling.
  • In areas that regularly see extremely low temperatures (around −30 °C and below), using a block heater for a few hours before starting is recommended so you can still keep idling time short.

Why long idling is not good

  • Extended idling wastes fuel and actually causes more engine wear than gently driving off, because the engine runs rich and combustion is less efficient.
  • Letting the car sit for 10–15 minutes may feel warmer inside, but it adds emissions, uses fuel, and does not meaningfully help a modern engine beyond the first minute.

Practical quick routine

  • Start the car, scrape windows, and buckle up: this usually takes about 30–60 seconds and is all the engine needs.
  • Drive off smoothly, keeping RPMs and throttle light for the first 5–10 minutes so the engine, transmission, and fluids can reach full operating temperature without stress.

TL;DR: For “how long should you let your car warm up in the winter,” the sweet spot for modern cars is about 30 seconds to 1 minute of idling, then gentle driving; only older carbureted cars or extreme cold really justify a few extra minutes.

Information gathered from public forums or data available on the internet and portrayed here.