An EV’s range refers to the number of miles it can travel on a fully charged battery, or a single charge.
All vehicles sold in the UK, including electric cars, are tested under the Worldwide Harmonised Light Vehicle Test Procedure (WLTP). Manufacturers advertise the range of their electric vehicles based on the findings of the WLTP testing.
However, the WLTP testing procedure is conducted in a laboratory setting, which means the driving is simulated, even if it includes “real world” conditions such as higher average driving speeds, longer journeys and faster acceleration sequences. The testing cycle does not include the use of air conditioning, headlights and other auxiliary equipment.
Recent research from Which? found that the actual range of an electric car to be on average 18% less than the official figure.
This means an electric car with a claimed range of 240-miles is more likely to offer a “real world” maximum range of around 196 miles.
“Overstated fuel economy is something petrol and diesel car drivers will already be aware of and we’ve found the same is true of electric vehicles,” said Emily Seymour, Which? Sustainability Editor.
“Our independent tests show electric cars fall an average of 45 miles short of official figures with some cars losing well over 100 miles of their claimed range.”
So, what affects the range of an electric vehicle?
1) Driving style
Whether you’re driving an ICE (Internal Combustion Engine) or EV, sensible driving is sure-fire way to increase your car’s fuel economy. Smooth inputs via the steering wheel and accelerator will put less stress on your car, resulting in a longer range. Stick to the speed limits and resist the temptation to experience too much instant torque (many EVs accelerate as fast as sports cars). Also, try to anticipate what’s going to happen in front of you by looking well ahead, so that you can slow down in good time.
2) Air conditioning
Most systems in a car, such as heating (including the seats and steering wheel) and air conditioning require electrical power from the battery. Try to limit excessive heating or cooling, as the higher the settings, the more battery energy is consumed. It is also recommended to pre-heat or pre-cool your car while it’s on charge.
3) Weather conditions
Batteries are at their most efficient when the outdoor temperatures is around 20°-30°C. They rely on chemical reactions to release electricity and power the car, but low temperatures slow these reactions down and reduce the performance of the battery. Cold weather can reduce an electric vehicle’s range by more than 20%, research by What Car? has found.
The heavier the car, the more energy is required to move it. EVs tend to be heavier than ICE cars anyway because the battery packs are so heavy. However, an EV’s range is further reduced when you have passengers on board, you’re carrying a heavy load or you are towing a trailer or caravan.
5) Battery degradation
This may be a factor, but it’s relatively small. Geotab, a Canadian fleet management company that has been tracking battery life data from 6,300 pure electric vehicles worldwide since 2014, found that across 21 different models (including the BMW i3, e-Golf, Nissan Leaf and Tesla Model S) the average battery capacity after five years was still 89.9% compared to a new car. Crucially, this includes early EVs that didn’t have the level of battery conditioning found in newer cars. For extra peace of mind, most manufacturers now offer an eight-year warranty on the battery.
Recent research by Bridgestone found that less than one in 10 UK motorists know the difference between standard tyres and EV tyres – and the money-saving benefits they offer. EV-specific are designed to deal with the weight increase of an electric vehicle (batteries are heavy) and the instant torque available – both strains on the tyre. Additionally, stick to the recommended tyre pressures. Underinflation will increase the tyre’s rolling resistance, and therefore electricity consumption.
7) Road topography
Driving up a hill requires more energy (and therefore battery power) than travelling along a flat road. That said, driving downhill does offer some compensation because the battery gets charged on the move via regenerative braking (a system which adds charge to the battery by harvesting energy otherwise wasted during braking and coasting).
It’s always been the case that the smoother the airflow around a car, the lower the drag and the less fuel you burn. It’s the same with EVs except that you use less battery range. The aerodynamic efficiency of a car’s shape is measured by its coefficient of drag (generally known as its Cd figure). The all-electric Mercedes-Benz EQS is one of the world’s most aerodynamically efficient road cars with a Cd of just 0.20.
So, the next time you see an electric vehicle advertised with a claimed range of 300 miles, take it with a pinch of salt. Depending on the factors above, the real-word range could be as much as 60 miles less – and that’s if you drive sensibly.