There is no fixed distance, but in winter a journey usually needs to last at least 15–20 minutes for most cars to reach full operating temperature. This allows engine oil to circulate properly, moisture to evaporate from internal components, and the alternator to recharge the battery after starting.

Shorter trips often end before this happens, meaning the engine, battery, and exhaust system repeatedly operate in a cold, inefficient state. Occasional longer drives are particularly important in winter to offset the cumulative effects of repeated short journeys. Excessive idling is not an effective substitute as once the engine is running smoothly, driving gently is better than letting the car idle for long periods.