Car insurance comparison site uSwitch said there are various items you could be keeping in your car that should be removed during a heatwave:

Diffusers: Most car diffusers are made of plastic. Prolonged heat can cause the plastic to warp, potentially damaging the diffuser and causing the oils to leak onto the interior of your car, resulting in stains. In extreme cases, some essential oils, particularly those with high flammability (like citrus oils), could pose a fire risk if they become too concentrated due to heat evaporation.

Fizzy canned drinks: Because of the increased pressure brought on by the warmer temperatures, carbonated cans left in a hot car can often burst. This could result in an expensive mess, as leakage could stain the upholstery.

Bottled drinks: It might seem logical to have a bottle of water in the car ready for a heatwave, however, there are widespread health concerns over the use of Bisphenol A and phthalates (BPA) in plastics, which act as binding agents to make the material more flexible. Leaving plastic-bottled water in a hot car may cause these agents to be released into the water. 

Cleaning gels: Although they’re a popular TikTok cleaning hack, most cleaning gels have a melting point. Leaving the gel in a hot car can cause the ambient temperature to exceed this melting point, turning the gel runny and sticky and making it likely to stain the interior of your car.

Hand sanitiser: These often contain alcohol which is flammable and could become a fire hazard.

Sun cream: Ironically, leaving sun cream in your car can be a bad idea when temperatures soar. The active ingredients can break down and cause the bottle to crack or perish, leaking a mess onto the upholstery that’s notoriously difficult to remove.

Chewing gum: If exposed to warm temperatures, chewing gum can lose its elasticity and viscosity, causing it to go soft or melt. If left on a seat, it could become stuck, resulting in damage to the interior of your car.

Pens: An overheating pen can burst and leave ink in the vehicle. Clean-up can be expensive and stains challenging to remove. 

Sweets and chocolate: Car snacks are common on summer road trips, however, they are prone to melting if left in warm temperatures over a long period. Again, this can result in stains to a vehicle’s interior.

Vapes: Although also posing a risk to the battery overheating, if a vape is left in a car in hot weather, you also run the risk of returning to a pretty big mess. The increased temperature will cause the liquid to thin, which can leak from the tank into your car.

Disposable lighters: With the lighter exposed to hot temperatures, the fluid and gases inside the lighter expanded, causing internal pressure to rise. This can result in potential fires that can damage the car or even harm those inside it.

Mobile phone and tablets: During warm spells the temperature in your car can rise to almost twice what it is outside. Your phone has a safe internal temperature it needs to maintain, but if it’s left in a hot environment for an extended period of time, it could end up shorting out, catching fire, or even exploding.

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