How Much It Really Costs to Cool Your Car With Air Conditioning

Air conditioning stopped being a pricey extra long ago and is now standard equipment on almost every car — even though it's a complex system that requires maintenance, adds weight, and puts extra strain on the engine. In return, though, drivers get a level of comfort worth understanding how to use wisely.

What to do before you set off

The air-con works hardest in the first few minutes of a drive, when it has to cool a cabin that's been baking in the sun — sometimes at temperatures above 50°C. That's why it's worth opening both doors before getting in and letting a cross-breeze clear out the hot air, even briefly.

Once the engine starts on a hot day, automatic climate control usually switches to recirculating the air already inside the cabin, since cooling air that's already partially cool is more efficient than pulling in hot air from outside. Once the target temperature is reached, the system eases off and lets fresh air back in. If your car doesn't have automatic climate control, it's worth replicating this sequence manually.

Electric car owners have an advantage here: the cabin can be pre-cooled via a smartphone app before you even get in. You won't get the benefit of airing out the interior this way, but the AC can be run while the car is still plugged in, which means it won't eat into your driving range.

What it costs in litres and crowns

According to tests by the German automobile club ADAC, in the first few minutes of operation — cooling the cabin from 31°C down to 22°C — test vehicles burned an extra 2.47 to 4.15 litres of fuel per 100 km. That spike, however, only lasts around three minutes, according to the club's findings.

Maintaining the set temperature afterwards costs extra fuel too, depending on driving style and the type of climate control — anywhere from 0.76 to 2.11 l/100 km in city driving, but only 0.09 to 0.66 l/100 km on the motorway. At a fuel price of 43 CZK per litre, that works out to roughly 4–28 CZK per 100 km on the motorway and 33–91 CZK in city traffic.

And what about EVs stuck in traffic?

There's a common worry that running the AC eats into an electric car's range on long trips — but tests suggest that concern is overblown. Unlike combustion-engine cars, an EV's AC compressor doesn't draw power from a running motor; it draws energy directly from the high-voltage battery. That means the motor doesn't need to run at all, even in a traffic jam, to keep the cabin cool. What's more, cooling the cabin and battery generally uses less energy than winter heating does.

The ADAC team simulated an extreme motorway traffic jam: for eight hours straight, a stationary Tesla Model Y had to fight rising heat while keeping the cabin at a set 20°C. The lab held a baseline temperature of 35°C, with special lamps simulating sunlight hitting the bodywork.

The test found that keeping the cabin comfortable required 1.3–1.5 kW of battery power, or 1.3–1.5 kWh of energy per hour. For the Tesla Model Y, that's only around 2% of battery capacity per hour, or a loss of about 8 km of range each hour. Over the full extreme eight-hour scenario, total energy use came to 12 kWh — 16% of the battery's charge, or a range loss of 64 km.

Source: novinky.cz