Guides / Guide

Real highway range: why your EV will not match the brochure

Every electric car has a claimed range, usually measured on the WLTP test. It is a fair way to compare cars, but it is not what you will get at 120 km/h on the N1.

Why highway range is lower

An EV is most efficient in town, where it recovers energy every time you slow down. On the highway, air resistance does most of the work, and it grows quickly with speed. Independent highway tests find that at 120 km/h many EVs fall roughly 30 to 40% short of their WLTP figure. In one 2026 test series, a BMW iX3 managed about 724 km at 90 km/h but about 511 km at 120 km/h, so the same car lost almost 30% of its range just by driving faster.

South African speed limits are 120 km/h on national roads and most drivers go a little faster, so this matters here more than in much of Europe.

What else takes range away

  • Roof racks and boxes: one test of a Škoda Enyaq found a roof rack cost about 19% of the range.
  • Towing: the same test found that pulling a caravan cut range by more than half. Do not plan to tow long distances with a standard EV.
  • Passengers and luggage: a full car costs a few percent, much less than speed does.
  • Cold: in a US study, range fell by about 12% at around minus 7 °C without heating and by about 41% with the heater on. Most South African drivers will not see that, but Highveld winter mornings and the Eastern Cape highlands do cost you a little.
  • Hills: climbing the Van Reenen’s Pass costs energy that you partly get back going down.

How Electrix handles this

On every car page and in the trip checker, we show an estimated highway range instead of the claimed one. We take the WLTP figure and multiply it by 0.7, then round to the nearest 10 km, and replace it with a figure from our own testing when we have one. That is a rule of thumb, not a measurement. It sits at the generous end of what independent tests find, so treat our estimate as a best case at 120 km/h rather than a guarantee. We change the factor in one place on the site if better evidence comes in.

How to use this when choosing a car

  1. Take the estimated highway range, not the WLTP figure.
  2. Subtract a reserve. We assume you never go below 10%, and you should not either.
  3. Remember that fast chargers slow down above about 80%, so on a long trip you will usually stop at around 10 to 20% and charge to 80%, not to 100%. That means your usable range between stops is about 60 to 70% of the battery.
  4. Run your actual route through the trip checker.

As a rough example, a car with a claimed range of 450 km has an estimated highway range of about 320 km, and about 200 to 220 km between fast-charging stops. That is fine for most trips, as long as you know where the next charger is.