Electric vehicles (EVs) share similarities with traditional cars, utilizing electric motors powered by batteries. Energy consumption for EVs is measured in kWh per 100 km, similar to fuel consumption in liters for gasoline vehicles. WLTP standards assess EV performance, but discrepancies exist between manufacturer claims and actual dashboard readings. Charging inefficiencies can lead to energy losses of up to 15%. Comparisons of consumption data across various driving scenarios are essential for informed consumer choices, yet many manufacturers provide limited information.
Electric vehicles share key similarities with traditional gasoline and diesel cars. They operate using one or more electric motors powered by a battery, replacing the need for gasoline in combustion engines. This makes it relatively straightforward to calculate the energy consumption of the vehicle by measuring the electricity used to propel it.
In European markets, fuel consumption for gasoline and diesel vehicles is typically expressed in “liters per 100 kilometers.” This metric allows drivers to easily understand how much fuel is consumed over a distance of 100 km.
For electric vehicles, the same principle applies, but we use kilowatt-hours (kWh) instead of liters. Thus, we discuss energy consumption in terms of “kWh per 100 km,” indicating how much electrical energy is utilized for every 100 km traveled.
Understanding WLTP Consumption Standards
Just like their gasoline and diesel counterparts, every new electric vehicle sold in Europe must undergo homologation tests to evaluate consumption and range, which follows the well-known WLTP (Worldwide Harmonized Light Vehicles Test Procedure) protocol. This standardized testing helps consumers understand the expected performance of their vehicles.
However, it has become apparent that not all manufacturers provide accurate representations of their electric vehicle consumption figures. It’s crucial to recognize that the WLTP consumption values shown on manufacturers’ websites often differ from the actual usage displayed on the vehicle’s dashboard. The dashboard readings reflect the consumption of electric motors and onboard electronics rather than the standardized WLTP figures.
Energy Loss During Charging
The WLTP consumption values incorporate not only the energy used for driving but also account for energy losses incurred during charging. When an electric vehicle charges at a station using alternating current (AC), energy is lost in the conversion to direct current (DC) and due to inefficiencies in electronic components. Depending on the model, these losses can be as high as 15%.
To illustrate, if you were to fill up a gasoline vehicle and 15% of the fuel leaked out, you would need to add that additional amount to fill the tank completely. A similar principle applies to electric cars, which is why the WLTP standard considers these energy losses in its consumption calculations.
Manufacturers usually provide three key figures: the combined WLTP range (in km), the urban WLTP range (in km), and the combined WLTP consumption (in kWh per 100 km). The WLTP range indicates the distance the vehicle can cover before the battery is fully depleted, while the combined cycle encompasses a mix of low-speed, urban, and high-speed driving conditions. Achieving the advertised range is most feasible when driving on secondary roads and in urban settings.
The combined WLTP consumption figure is derived from this mixed cycle and reflects how much energy is consumed during the various driving conditions described, including the losses related to charging.
Moreover, the WLTP standards provide five additional consumption metrics for different driving scenarios: low speed, medium speed, high speed, very high speed, and urban conditions. This wealth of data facilitates comparisons across various electric vehicles under different driving circumstances.
Interestingly, some electric cars can consume less electricity at higher speeds than others, despite having higher mixed consumption figures. Factors such as aerodynamics and motor efficiency play significant roles, which we will explore further.
Unfortunately, many manufacturers tend to offer only limited consumption data, frequently providing just the mixed cycle consumption figures. Brands like Volkswagen are exceptions, offering a complete set of consumption data across different driving scenarios, which is vital for consumers interested in purchasing an electric vehicle.
For example, consider the Volkswagen ID.4 with a 77 kWh battery and the Porsche Taycan featuring a larger 97 kWh battery. The ID.4 has a mixed consumption figure of 15.8 kWh per 100 km, while the Taycan is rated at 17.1 kWh per 100 km. At first glance, one might assume the ID.4 is more efficient; however, at very high speeds, the numbers tell a different story. The ID.4 consumes 20.6 kWh per 100 km compared to the Taycan’s 18.1 kWh per 100 km under similar conditions.
This discrepancy arises because the Porsche’s superior aerodynamics allow it to perform better at higher speeds, where aerodynamic drag becomes a significant factor impacting energy consumption. Conversely, at lower speeds, weight and motor optimization are more critical considerations.
For consumers wishing to compare electric vehicles based on their long-distance consumption, the WLTP standard serves as a helpful guideline. Unfortunately, many manufacturers provide limited data, making it challenging to make informed decisions.
For instance, Tesla has been criticized for not providing comprehensive consumption data. While they do present the WLTP range for the mixed cycle, the urban range and detailed consumption figures are often absent or insufficiently detailed. This lack of transparency can be frustrating for potential buyers looking to understand the true efficiency of Tesla vehicles.
Making Informed Comparisons
When evaluating consumption figures between different models, such as the ID.4 and the Taycan, it’s essential to avoid rushing to conclusions. A closer look at Volkswagen’s ID.7 demonstrates that aerodynamics is not the sole factor influencing consumption differences across various driving cycles. The ID.7 consumes 13.6 kWh per 100 km in the mixed cycle and 17.1 kWh per 100 km on the highway, illustrating a significant 26% increase, while the Porsche Taycan shows only a 10% increase in consumption under similar circumstances.