Why WLTP range doesn't match real life
WLTP is a standardised laboratory cycle run at gentle average speeds and a mild ambient temperature. It exists so you can compare cars on a level playing field, but it was never meant to predict how far you will go on a Tuesday in February.
Real range depends on four physical variables the lab ignores or softens: your actual speed, the outside temperature, your heating or cooling demand, and the age of the battery. HonestRange computes each one from first principles rather than discounting WLTP by a flat percentage.
The physics: speed, drag and mass
At any road speed, the motor must overcome two forces: aerodynamic drag, which rises with the cube of speed, and rolling resistance, which is roughly constant. At 30 mph, rolling resistance dominates; by 70 mph, aero drag is several times larger. That's why motorway range is always shorter than town range — there's no fault or trick, just physics.
Mass matters too, especially on hilly routes. A heavier car needs more energy to climb a gradient, and regenerative braking recovers only part of that on the descent. Our model uses each car's kerb weight, drag coefficient and frontal area — see the full equations on the methodology page.
Temperature and cabin heating
Cold weather hits range from two directions. First, cold air is denser, which raises aerodynamic drag at any speed. Second, the cabin heater draws power the battery would otherwise spend on miles.
A resistive PTC heater can pull several kilowatts; a heat pump does the same job for roughly half the energy above about −5 °C. That's why our heat pump comparison shows a visible winter-range advantage for heat-pump cars.
Battery degradation and state of health
Every EV battery loses capacity over time. A pack that started at 60 kWh usable might hold 54 kWh after five years — so its range ceiling drops proportionally. Liquid-cooled packs typically degrade a couple of percent a year; air-cooled packs like the early Nissan Leaf lose more.
Our model estimates state of health from the car's age and mileage using an exponential-approach curve calibrated per chemistry and cooling type. You can set the exact age and odometer on any car page to see the resulting real range. For more, see how much degradation is normal.
Motorway vs. town: the practical gap
Because drag rises with the cube of speed, the energy to maintain 70 mph is roughly double that at 50 mph from drag alone. Add a headwind and the effective airspeed climbs further. Every car page shows separate mild, winter and motorway range cards — not one headline figure that hides the spread. See how far can an EV go on the motorway for a worked example.
What you can control
You can't change physics, but you can manage it. Preheating the cabin while still plugged in spends grid energy instead of range. Keeping speed at 60 rather than 70 on the motorway can add meaningful miles. And choosing a car whose drag coefficient and mass suit your driving pattern matters more than chasing the biggest battery. Use the model comparison to see which cars hold up best in the conditions you actually drive.