Drag coefficientCd
Drag coefficient measures how slippery the car's shape is through air. Lower is usually better for motorway efficiency. It matters because official range is only the controlled test case. Real trips change with speed, temperature, tyres, road conditions, payload and how often you can charge.
How to compare it
Compare Cd with frontal area. The real aero load is closer to Cd times frontal area, so a sleek large SUV can still push a lot of air.
- Use official range for same-cycle comparison.
- Estimate your own motorway, winter and city mix.
- Aerodynamics and tyres can matter as much as battery size.
What changes it
Range moves because the car is spending energy against air, rolling resistance, heating or cooling, elevation, rain, load and speed.
- High speed raises aerodynamic losses sharply.
- Cold weather adds cabin heat demand and can reduce battery output.
- Tyres, roof boxes and rain can change efficiency without changing the battery.
Common trap
A low Cd headline does not guarantee low consumption if the car is wide, tall, heavy or fitted with inefficient tyres.
- Cold weather and high speed can change the result more than expected.
- Roof boxes and wide tyres can quietly consume range.
Drag coefficient: why real range moves
Range moves with air resistance, temperature, tyres, speed and payload, even when the battery size is unchanged.
Drag coefficient across EVRadar
Based on 306 published cars
Lowest
0.17 Cd
Typical
0.3 Cd
Highest
0.656 Cd