- Park in shade to lower interior temperatures and reduce AC load.
- Ventilate 1–2 minutes before starting, then use recirculation AC after closing windows.
- Start at 24–25°C and gradually lower the cabin temperature.
- At speeds above 50–60 km/h, AC uses less fuel than open windows.
Summer brings not only high temperatures but also extra fueling costs for drivers who don’t pay attention to where they leave their car. A recent study from the United Kingdom sheds light on an issue many ignore: parking in direct sun affects not only comfort but also your wallet.
With increasingly frequent heatwaves in Romania, understanding this phenomenon becomes essential for anyone who wants to save fuel with minimal effort. The solution is simpler than you think and costs exactly zero.
Why fuel consumption increases when the car sits in the sun
The mechanics behind this phenomenon are straightforward. When the vehicle sits for hours exposed to direct sun, interior temperatures can easily reach 50–60°C. The plastics on the dashboard, the seats, and the cabin air absorb and reemit heat, turning the car into a real oven.
On starting the engine and turning on the air conditioning, the AC compressor must work at maximum capacity to cool the interior quickly. The AC compressor is driven by the engine via a belt, which means the engine must provide more power to spin it. This extra effort translates directly into higher fuel consumption.
Real impact on consumption
British studies show that heavy use of air conditioning to cool an overheated interior can increase consumption by 5–10% in the first 10–15 minutes of driving. In urban traffic, where engine efficiency is already reduced, the percentage can be even higher.
For a driver who does this daily, the difference adds up. With an average consumption of 7 L/100 km and 20,000 km traveled per year, that’s about 70–140 liters of extra fuel per year, equivalent to 500–1000 RON at current prices.
Practical solutions to save fuel in summer
Park in the shade
The main method of saving is extremely simple: look for shaded parking spots. Whether it’s under a tree, a building, or an underground lot, any protection from direct sun makes a difference.
If shaded parking isn’t possible, orient the car so that the windshield is not directly in the sun’s path. Use a windshield sunshade—costs 20–50 RON and can reduce interior temperature by 10–15°C.
Ventilate intelligently before starting
Before starting the engine and the AC, open all windows and doors for 1–2 minutes. Let the hot air escape naturally. Then start the car with the windows down and the AC at maximum power in recirculation mode. After 2–3 minutes, close the windows. This method significantly reduces the time the compressor works at maximum capacity.
Use the AC efficiently
Do not set the temperature to the minimum immediately. Start at 24–25°C and gradually lower it. The climate control system does not cool faster at 18°C than at 22°C—it will simply run longer to reach the lower temperature.
On the move, at speeds above 50–60 km/h, air conditioning consumes less than driving with the windows open due to increased aerodynamic drag.
Other summer habits that cost you fuel
Tire pressure
High temperatures affect tire pressure. Hot air expands, and pressure can rise by 0.2–0.3 bar. Paradoxically, many tires end up underinflated in summer because drivers neglect regular checks. Underinflated tires increase consumption by 3–5%.
Check the cold pressure in the morning, according to the manufacturer’s specs. In summer, you can add 0.1–0.2 bar over the recommended value to compensate for temperature differences.
Unnecessary car use for short trips
A cold engine consumes significantly more fuel—up to 50% more—during the first 2–3 km. For trips under 2 km, especially in the city, walking or cycling is much more economical.
If you must use the car for short distances multiple times, try to group them into a single trip to keep the engine at operating temperature.
Roof boxes and open tailgates
Roof luggage increases consumption by 10–20% at highway speeds due to aerodynamic drag. If you don’t use it, remove it. Likewise, an open or partially open rear cargo area can add 5–10% to consumption.
Long-term benefits
Fuel savings aren’t the only advantage of smart parking. Prolonged sun exposure accelerates interior deterioration— upholstery fades, plastics crack, the steering wheel and gear knob become unbearably hot.
A climate control system forced to run constantly at max capacity wears out faster, and repairs can cost approximately 1,500–3,000 RON for a full recharge or replacement of the compressor.
Conclusion
Saving fuel in summer doesn’t require investments or major changes. Awareness of the impact of parking in the sun and a few simple habits can significantly reduce consumption. Annually, the difference can amount to hundreds of RON, and comfort and safety also gain.
In the context of rising fuel prices and climate change, every responsible driver should consider these practices—not only for personal savings but also for reducing the carbon footprint of daily commutes.
