• Understanding range
• EPA
• WLTP
• CLTC

Understanding range

For many, the range is the most critical aspect of an EV. In this guide, we explain what factors affect the driving range of EVs and why new EV owners often experience a lower range than expected.

The range of electric cars is typically given as a WLTP range (Worldwide Harmonised Light Vehicles Test Procedure) in Europe, EPA in the US, and CLTC in China.

The models available today (summer 2023) have a rated range between approx 200km and 900km.

The most critical aspect of range is how large the battery is. A larger battery means more energy to use.

Today’s model has a battery size between approx 40kWh and 230kWh, with the majority being 60-100kWh. The table below shows the usable battery size of some of the most popular models.

You can see all models sorted on net battery size in our EV database.

But the battery is not the only factor in the stated range. Another critical factor is how efficient the car is. And with efficiency, it means how much energy the EV uses from the battery for a given distance. It is typically stated in Europe as kWh/100km, indicating how many kWh is needed to drive 100km. In the US and the UK, it is rated as miles per kWh, meaning a calculation of how far you can go with 1 kWh.

The table below shows the calculated kWh/100km consumption and miles/kWh for different EVs according to the WLTP combined rating.

What affects the rated consumption?

The efficiency or consumption is affected by many attributes of the car.

Aerodynamic drag

The aerodynamic drag affects how much energy is needed to move. The shape of the body affects it, but also the design of the wheels. The Mercedes Vision EQXX is currently the EV with the lowest drag coefficient with a Cw value of only 0.17

Calculating how much energy is needed to overcome aerodynamic drag is possible if you know a model’s drag coefficient and the frontal area size.

Below, you see some examples from various models.

The graph below shows how much aerodynamic drag consumption causes for the different models.

The table below shows aerodynamic drag consumption on three different Audi models and Mercedes EQS.

You see how the Mercedes EQS saves a lot of energy at high speed compared to the SUV because of less aerodynamic drag.

Mercedes has focused on low aerodynamical drag. But it has drawbacks since many complaints about EQS design.

Rolling resistance

Rolling resistance, sometimes called rolling friction or rolling drag, is the force resisting the motion when a body (such as a ball, tire, or wheel) rolls on a surface.

The rolling resistance is affected by the tires’ width, the car’s weight, the tire compound, and the tire pressure.

Many manufacturers offer narrow tires as a base to advertise the best possible range possible for the model. The disadvantage is less grip. Other manufacturers offer staggered setups with less wide front tires than rear tires. This setup increases range compared to the same width on all four tires.

Some tire producers have started producing specific tires for EVs with low rolling resistance that affects range.

See below for a detailed test describing the difference between EV-optimized and regular tires.

Weight

A heavier car requires more energy to move.

The efficiency of the drivetrain/motors

Electric motors are very efficient by default, but different motor technologies still differ in consumption.

Permanently excited synchronous use less energy in use but have higher coasting resistance. Induction motors use more energy to move but have almost zero coasting resistance.

Newer cars often combine these two techniques having a rear synchronous motor always in use and an induction motor in front.

The internal resistance of the battery

The internal resistance in the battery causes heat loss in the battery.

Factors vary based on selected options

How the manufacturer designed the EV gives many of the above factors. Because of its body shape, the e-tron Sportback has less drag than the e-tron SUV. But other factors are affected by the equipment you add to your car.

The buyer can configure some EVs with many options affecting the rated range. This possibility is typical for brands like Porsche and Audi.

Buying wider tires will give you a higher consumption and a shorter range. Adding a panoramic roof can increase consumption and reduce the driving range.

The diagram below shows how adding the car’s max options increases the rated WLTP consumption and reduces the range on some Audi models.

The diagram shows that an Audi e-tron 55 consumes 19.61 kWh/100km in the basic trim but 23.44 kWh/100km in the top trim. It reduces the range from 441km (274 miles) to 369km (229 miles).

What affects the real-world consumption

In the real world, getting the same range as given by WLTP or EPA is almost impossible. That range the manufacturer base on ideal driving conditions with specific behavior.

Road condition

Road conditions are one of the factors that affect consumption. If it is dry tarmac, the rolling resistance is much lower than if the road is wet or packed with snow.

The speed

High speed increases consumption because of higher drag.

The temperature

Several factors affect the range when temperature changes.

AC consumption

Warm and cold weather will increase the car’s consumption of air condition systems. On a freezing day, you could spend a significant amount of the battery to heat the cabin.

The same is true on hot days when AC tries to cool down the cabin.

Depending on the model typical the MAX power that the AC can draw from the battery is 5-10kW at max.

The table below shows how different average AC consumption levels for heating/cooling will affect driving consumption. Driving slow with heater blasting will affect the range the most.

The table below shows how different models are affected by 2KW AC at different speeds.

A model with low consumption in perfect conditions is affected more in percent.

Internal resistance in the battery

When the temperature gets low enough, the electrolyte fluid becomes more viscous, which slows down the chemical reactions and reduces the electron flow.

The higher internal resistance causes more heat loss and reduces the usable energy you can draw from the battery. This effect can reduce the usable battery by several kWh.

This effect affects not only the range an EV can get on a charge but also how quickly it can recharge.

Since the chemical reactions are slower, the manufacturer programs the battery to accept less power when.

To prevent this, modern EVs have battery heating and cooling systems that try to maintain an optimal temperature range for the battery pack, usually between 40 and 115 degrees Fahrenheit.

Many models support the precondition of the battery before charging.

However, these systems also consume some battery power, especially when heating the battery in cold weather.

For example, suppose you have a battery with 77kWh net capacity, and the internal resistance only makes it possible to draw 72kWh out of the battery. In that case, the range is reduced by 6.5% before factoring in increased consumption.

Air density

If it is cold, the air is denser and has a higher aerodynamical drag.

The driving style

You, as a driver, can improve the range a lot.

• Look ahead and coast as much as possible
• When needing to reduce speed, reduce when possible so early that you only use recuperation.

How does the range indicator work?

Most EVs have a range indicator showing in miles or km how much range the car has left before the battery is empty.

This range indicator works differently on different brands.

Range indicator based on rated range and SOC

This type of range indicator bases the range on the rated range and the battery’s state of charge. If the rated range is 300 miles, and you have a 50% state of charge, the car will indicate a range of 150 miles. It does not consider driving history or environment. The type of indicator will show the same range in winter and summer and does not care how you drive.

So if you are driving Miss Daisy on country roads or racing on the Autobahn every day, a fully charged EV will show the same range.

This type of range indication is useless for the driver but gives a false promise of the range.

Tesla is a brand that uses this range indication and has been criticized by many.

Range indicator based on driving history and environment

Many EV manufacturers have range indicators that base the estimated range on driving history and environment.

They typically try to learn from previous trips, which causes questions about the range from owners since the range varies and drops when the driving condition worsens.

So how does this type of range indicator work?

The range indicator base its range on the following data

• Average consumption on the previous distance driven (typically last 100km)
• Outside temperature
• The state of charge (how much the battery is charged)
• The planned route in the navigation system

So assume you have an e-tron 55 with 86.5kWh battery and charge it to 100%.

If your average consumption were 25kWh/100 on the previous trips, the range indicator, or GOM (guessometer) that many call it, would calculate you would have a range of 346km. If your average consumption were 20kWh/100km, it would calculate 432km. And if you like speed and had an average of 30kWh/100 km, your estimated range would be 288km.

But this is the best guess based on previous trips. If you change your behavior on the next trip, the range calculated would be wrong. If you have done many short trips in cold weather, you would have spent lots of energy to heat the car. But this average consumption is irrelevant if you take a long drive the next day. The vehicle would then underestimate the range.

If you have defined a route in the car navigation system, the car will adjust the range based on elevation and the road ahead.