With temperatures soaring to nearly 40°C this week, drivers are making critical mistakes when entering hot cars, wasting fuel and risking their safety. Tom Preston, Managing Director at Hippo Leasing, has shared essential advice on keeping cars cool during the heatwave.
Why You Shouldn't Turn On AC Immediately
“When people step into their car, many will mistakenly turn the A/C on right away thinking that it will cool them down,” Preston said. Instead, he recommends opening windows for a minute before turning on the AC to let trapped hot air escape. “Keep windows open for the first minute of driving, too. Whilst you have them open, point the air vents down towards the footwells initially. This is because cool air pushes warm air up and out. Once your car feels cooler, close the windows. Otherwise, you’ll simply pump all the cold air outside.”
The Recirculation Button: A Double-Edged Sword
Once the car is cooler, press the recirculation button to recirculate cooled air instead of drawing in hot air from outside. However, leaving it on for more than 30 minutes can cause CO2 buildup, making the driver drowsy. “Don't leave it on for too long. If your car is full, CO₂ can build up, which can make the driver drowsy. So, switch it off after around 30 minutes, or crack open a window,” Preston warned. Also avoid using it in wet weather as it traps humidity and fogs windows. In heavy traffic, it's worth switching on to block fumes from other vehicles.
Windows vs. AC: Which Is More Fuel-Efficient?
“During a heatwave, A/C is 100% the way to go. While the breeze might feel nice, opening your car windows doesn’t actually cool down the temperature – you’re just moving air around. In contrast, A/C actually removes heat and moisture from the air, resulting in a cooler, more comfortable temperature,” Preston explained. In milder heat, opening windows can be effective below 45mph, as drag is minimal. “Above 45mph, though, open windows create significant drag, so at that point, A/C is actually the more fuel-efficient choice.”
Key Takeaways for Drivers
- Open windows for a minute before turning on AC to expel hot air.
- Point vents downward initially to push warm air up and out.
- Use recirculation button but turn off after 30 minutes to prevent CO2 buildup.
- Avoid recirculation in wet weather to prevent fogging.
- Use AC above 45mph for better fuel efficiency.
By following these tips, drivers can stay cool and safe while saving fuel during the heatwave.
