Summer Driving Tips for Keeping Your Car Cool

Why Heat Is Harder on Your Car Than You Think

We spend most of the year worrying about frost, salt and cold starts, but a British heatwave can be just as punishing on your car. Tarmac temperatures can climb well above the air temperature, and everything under your bonnet is working in an oven while you sit in stationary traffic on the school run. Rubber perishes, fluids evaporate, batteries weaken and cooling systems that have quietly coped all winter suddenly find themselves asked to do real work.

The good news is that most summer breakdowns are entirely preventable. Twenty minutes with a tyre gauge and a torch now will save you a great deal of grief on the hard shoulder later. Here are the checks worth doing before the next warm spell.

Check Your Tyres Before the Mercury Rises

Tyres are where heat does its quietest damage. As the air inside them warms, pressure rises — roughly one psi for every 10°C increase — so a tyre set correctly on a cool morning can be noticeably over-inflated by mid-afternoon. That matters because over-inflation reduces the contact patch, wears the centre of the tread and makes the car feel skittish.

• Check pressures when the tyres are cold — before you drive, or at least three hours after your last journey. Use the figures in your handbook or on the driver's door pillar, not the maximum moulded on the sidewall.
• Adjust for load. If you're heading off with a boot full of luggage and bikes on the roof, most cars specify higher rear pressures. This is worth twenty seconds of your time and makes a real difference to stability.
• Inspect the sidewalls. Look for cracks, bulges and grazes. A bulge means internal damage and the tyre needs replacing, full stop.
• Check tread depth. The legal minimum in the UK is 1.6mm across the central three-quarters of the tread around the whole circumference, but performance drops off well before that. If you're near the limit, change them before the holiday.
• Don't forget the spare — or the can of sealant, which has a use-by date and shouldn't be relied on for a long trip.

Keep an Eye on the Cooling System

Overheating is the classic summer failure, and it almost always announces itself in advance. Check the coolant level in the expansion tank when the engine is stone cold — never remove the cap while the system is hot, as pressurised coolant can scald badly. The level should sit between the MIN and MAX marks.

Top up with the correct mix of antifreeze and water — usually around 50/50 — rather than plain water, which lowers the boiling point and offers no corrosion protection. While you're there, look for crusty white or pinkish deposits around hoses and joints, and check the hoses themselves for softness or cracking. If your temperature gauge ever starts climbing, turn the air conditioning off, put the heaters on full hot, and pull over safely as soon as you can.

Don't Neglect Your Air Conditioning

Air conditioning isn't a luxury in a hot car — it keeps you alert and comfortable, and it also demists far faster in a summer downpour. Systems lose a small amount of refrigerant every year, so if yours is blowing cool rather than cold, a regas is likely due.

• Run it all year round, even in winter, for ten minutes a week. This keeps the seals lubricated and prevents the compressor from seizing.
• Change the pollen filter if the airflow smells musty or feels weak. It's an inexpensive part and often easy to reach behind the glovebox.
• Cool down smartly: open the windows for the first minute to flush out hot air, then close them and use recirculation before switching back to fresh air.
• Park in the shade where you can, and use a windscreen sunshade. It makes a genuine difference to how quickly the cabin becomes bearable.

The Underrated Checks: Battery, Oil and Screen Wash

Heat is actually harder on batteries than frost is. It accelerates the internal corrosion that eventually kills them, so a battery that's been sluggish for months often gives up on the hottest day of the year. Check the terminals are clean and tight, and have the battery tested if it's more than four or five years old.

Engine oil thins as it gets hotter, so an already-low level becomes more of a problem. Check it on level ground with the engine cold, and top up with the grade specified in your handbook. Finally, mix proper screen wash concentrate rather than plain water — summer means insects, dust and tree sap, and a weak mix won't shift them.

Pack Smart and Plan Your Journey

Before a long run, give yourself a small kit: a couple of litres of water, a phone charger, high-visibility vest, warning triangle and a basic first aid kit. Keep a bottle of coolant or pre-mixed antifreeze in the boot too. Plan breaks every couple of hours, travel earlier or later to avoid the worst of the heat, and never leave children or dogs in a parked car, even with the windows down. And be careful where you park — a hot exhaust or catalytic converter can set dry grass alight.

None of this is complicated. A little attention now means you spend the summer enjoying the drive rather than watching the temperature gauge.