Most long-trip advice was written for petrol cars, so it tells you to check the oil. Your EV hasn't got any. What it has got is a set of components that a motorway run stresses in ways daily commuting never does — and two of them, brakes and tyres, fail in a pattern that is specific to electric cars and catches people out every summer.

Brake Fluid: The One Nobody Expects

Regenerative braking means your friction brakes barely work. That sounds like good news, and for pad and disc wear it is. For the hydraulic system it isn't.

Brake fluid is hygroscopic — it pulls moisture out of the air through the seals and hoses, slowly, whether you use the brakes or not. Moisture lowers the boiling point. In a petrol car you'd never notice, because the pads wear out and the system gets inspected and topped up every couple of years. In an EV the pads can last 60,000 miles, so nobody looks.

Then you load the car with four people and luggage and take it down a long descent — the Heads of the Valleys, a Lake District pass, an Alpine hairpin — where regen alone can't hold the speed and the friction brakes finally do the work they were built for. Wet fluid boils, you get a soft pedal, and it happens at the worst possible moment.

The check takes two minutes with a moisture tester. Anything over 3% water and the fluid wants changing before you go. Most manufacturers say every two years regardless of mileage, and on an EV that interval matters more, not less.

Tyres: Heavier Car, Instant Torque, Faster Wear

An EV carries several hundred kilos of battery low in the floor, and delivers full torque from a standstill. Both of those eat tyres. Wear rates 20–30% faster than an equivalent petrol car are normal, not a fault.

Before a long trip, check three things:

  • Tread depth across the width, not just in the middle. Inner-edge wear is common on EVs and invisible unless you turn the wheel to full lock and look.
  • Pressures, set for a loaded car. There's a second set of figures on the door pillar for full load. Under-inflated tyres on a heavy car run hot, and they cost you range on top.
  • Age. The four-digit code on the sidewall gives week and year. Rubber hardens with time regardless of tread, and a well-treaded eight-year-old tyre is not a motorway tyre.

The 12V Battery — What Actually Strands EVs

The traction battery gets all the attention. The little 12V one under the bonnet is what leaves people stuck in service station car parks, because it runs the contactors that connect the traction battery in the first place. Flat 12V, and a car with 80% charge won't wake up.

They typically last three to five years and give almost no warning. A load test before a trip is quick and tells you far more than a voltage reading does.

Coolant — Yes, Your EV Has It

Most EVs run a liquid thermal management circuit for the battery pack, and often a second for the motor and power electronics. Sustained motorway speed in August, followed by rapid charging at a hot service station, is the hardest thermal work your car ever does.

Low coolant means the pack can't shed heat, and the car protects itself by cutting charging speed — so your 20-minute stop becomes 45. Check the level in the expansion tank when the car is cold. It's not a job for a hot pack.

Know Your Real Range Before You Plan Around It

Trip planning apps work from the car's original quoted range. If your battery is at 88% state of health, every leg is 12% shorter than the app thinks — and that gap shows up as a missed charger, not a rounding error.

A verified state of health figure turns route planning from optimism into arithmetic. It's also the number to know before you tow anything or load the car to the roof.

The Pre-Trip List

  • Brake fluid moisture tested — under 3%
  • Tyre tread across full width, pressures set for a loaded car, sidewall dates checked
  • 12V battery load tested
  • Battery and motor coolant levels checked cold
  • Cabin filter — a summer's worth of pollen makes the air con work harder, and that costs range
  • Battery state of health verified so your range planning matches the car
  • Charging cables and adapters actually in the boot

The Bottom Line

Electric cars need less maintenance, not none — and the things they do need are the ones no routine catches, because there's no oil change forcing an annual look under the bonnet. Brake fluid and the 12V battery are the two that turn a good holiday into a recovery truck, and both are cheap to check and cheap to fix before you go.