Every driver in Germany knows the pain at the pump. We compare prices, drive efficiently, and try to avoid unnecessary trips. But we often overlook one of the biggest factors influencing our fuel consumption: the weather. Whether it's a freezing winter morning, a scorching summer day, or a stormy drive to the coast, the weather can increase your fuel usage by 10%, 20%, or even more.
But why is that? In this guide, we'll explain the science behind it in a simple and understandable way, give you concrete examples from everyday German life, and show you clever tricks to beat the weather surcharge and save real money.
By far the largest weather-related increase in fuel consumption occurs in winter. On a cold morning, your car has to work harder to get going—and that costs fuel. Several factors come together here:
Imagine trying to walk through waist-deep honey. That's exactly how your engine feels on a cold morning. The engine and transmission oil are thick and viscous at sub-zero temperatures. The engine has to expend much more energy to fight this internal resistance until everything reaches its operating temperature. This process can lead to a significant increase in consumption over the first few kilometers.
An internal combustion engine operates most efficiently at its optimal operating temperature (around 90°C / 194°F). In winter, it takes much longer to reach this temperature. During the warm-up phase, the engine management system deliberately injects more fuel (similar to the old "choke") to keep the cold engine running and to heat up the catalytic converter more quickly. This is a huge factor, especially on short trips.
In winter, additional electrical consumers are almost always running: lights, rear window defroster, heated seats, heated steering wheel, and the fan on high. All this electricity is generated by the alternator, which is driven by the engine. A higher load on the alternator means more resistance for the engine—and that costs extra fuel.
Cold air contracts. This causes the pressure in your tires to drop. Underinflated tires increase rolling resistance because the tire "flexes" more. Just 0.5 bar too little pressure can increase consumption by up to 5%.
In summer, the main culprit for increased fuel consumption is easy to find: the air conditioner (A/C).
An air conditioner works like a refrigerator. A compressor, driven by a belt from the engine, compresses a refrigerant. This process requires significant mechanical energy. So when you press the A/C button, the engine has to do extra work, which directly increases fuel consumption.
The extra consumption from the A/C is not constant. It depends heavily on the outside temperature and the desired cooling level, and can range from 5% to as much as 25%.
Wind is an often-underestimated factor. At speeds above 80 km/h (50 mph), air resistance becomes the largest force your engine has to overcome. A strong headwind is, in physical terms, no different from driving uphill.
Even a moderate headwind of 25 km/h (15 mph) can increase fuel consumption at highway speeds by up to 10%. During a storm, this figure can rise to over 25%. High-sided vehicles like SUVs and vans, or cars with roof boxes, are particularly susceptible. A roof box alone can already increase consumption by 10-15%—combined with a headwind, it becomes even more dramatic.
Wet surfaces also increase consumption, albeit to a lesser extent than cold or wind.
Although you often drive slower in the rain, which in principle saves fuel, the increased rolling resistance and the use of the blower, lights, and wipers usually cancel out this effect.
You can't change the weather, but you can change your reaction to it. With these tips, you'll save real money:
The weather is a silent but powerful factor that influences your fuel bill. By understanding the connections and adapting your behavior, you regain control. A quick look at the weather forecast before a drive is not just a matter of safety, but also a smart economic decision. Drive smart, drive proactively, and don't let the weather drain your tank any longer.