Overview
- The tip, which resurfaced in UK coverage on Wednesday, May 27, 2026, began as a viral clip by mathematician Hannah Fry and has been widely reported again during the heatwave.
- Fry’s recommended method is to wind down one nearside window and rapidly open and shut the driver’s door several times to push hot air out of the cabin.
- Physicists explain the effect as the moving door sweeping air away, creating a local low pressure that sets up bulk flow and draws hot, trapped air out of the car.
- Reporting and a hands‑on test show the hack can make the cabin feel cooler in a few repeats but its success depends on outside air being cooler and on doing the door motion quickly and with a rear window open.
- Coverage stresses limits and context: most new cars have air conditioning so the trick is mainly for AC failure or a quick pre-journey flush, the Met Office links the UK heat to high pressure and adiabatic warming, and consumer group Which? offers complementary fan advice for homes.