Simple car trick that cools your vehicle ‘faster than aircon’ in a heatwave

The UK is currently in the grip of a heatwave, and one simple car cooling hack can help cool down your car in no time – and it’s said to be even more effective than using the aircon

The UK is currently in the grip of a sweltering heatwave, with a red alert for hot weather issued across more than 50 areas this week. When temperatures soar this high, the interior of your car can become unbearably hot, making it very unpleasant the moment you climb in.

The first thing most people reach for when getting into a scorching car is the air conditioning. But this may not actually be the fastest or most efficient way to cool things down.

A far handier tip was recently shared by Capital FM presenters during a chat about heatwave hacks, and there’s even solid science to back it up.

Presenter Sian Welby raised the tip, which she’d originally spotted shared by Professor Hannah Fry on social media, and broke down exactly how it works.

She said: “So you’re in the driver’s seat. You’re going to wind down the window of the back left seat. Then you’re going to get out of your driver’s seat and just open and close the door [four times.]

“You get back in the car, it’s cool.”

It may sound odd, but there’s a scientific principle underpinning this trick known as fluid dynamics, according to Hannah. In her own YouTube video, she urged Brits to ditch the car aircon entirely in favour of this far more effective approach.

She joked that you might look like ‘a bit of an idiot’ while swinging the door back and forth, but insisted it’s well worth it in the long run. Hannah explained: “The reason why it works is that when you open and close the door – especially if you do it quickly – the door sweeps out all of the air that’s in its way, creating this area of low pressure that you get here.

“And then that sets up something called bulk flow which is where all the hot, sweaty, horrible air inside the car is drawn outwards.”

Gesturing towards the open window, she continued: “The only way to refill it is with nice, fresh, easy air from over that side.

“It only takes about two or three goes, and suddenly it’s actually beautifully temperate.”

The video’s comments section was flooded with grateful responses, with many viewers confirming the trick genuinely works. One person wrote: “I used to do this without knowing the science behind it– it just seemed like the thing to do and it helps.”

Another said: “Been doing this for 20 years with the blind belief that it’s better than just opening all the windows. Thanks for the scientific pardon.”

And another commented: “This is a top tip, I’ve been doing this for years and can absolutely confirm it works as described.”