The electric vehicle market is now blooming with variety. As a customer, you’d want to spend your money on the best electric car. For many people, the best car means the car that has the best driving range.
The driving range is a measure of how far the car can go until it runs out of juice and completely stops. But, how do we actually know the car’s true driving range before we buy it? Should we trust automobile manufacturers driving range numbers? How do they even get those numbers?
The United States Environmental Protection Agency (EPA)
As with any measurement system, a standardized metric is generally a good idea. For electric vehicles, each country or region usually has its own standards. Out of all EV range standards, many favor the US EPA rating system because it is more comprehensive than the rest.
Every vehicle must undergo a series of tests to achieve its EPA-rated range. The general testing procedure is to charge the battery fully, park the vehicle overnight, and then, the following day, drive the vehicle over successive city cycles until the battery is empty.
After running successive city cycles, the battery is then recharged from a normal AC source, and the vehicle’s energy consumption is determined (in kW-hr/mile or kW-hr/100 miles) by dividing the kilowatt-hours of energy needed to recharge the battery by miles travelled by the vehicle. The recharge energy includes any losses due to inefficiencies of the manufacturer’s charger.
The city driving range is determined by the number of miles driven over the city cycle until the vehicle can no longer follow the driving cycle.
The motivation behind the EPA’s rating is to give a strong basis for comparing electric vehicles. There are three EPA testing environments:
This estimate represents how people drive electric vehicles daily as they commute in cities. This test includes driving in the morning and driving in the busy traffic, following stoplights, and other road signs.
This estimate represents how people drive electric vehicles on interstate highway roads. The highway usually has free-flowing traffic with no stops, but moderate-to-high wind speeds, which put the car’s aerodynamic prowess to the test.
The testing method is the same with the City testing method, but instead of city streets, the car is driven on highways.
This estimate represents a combination of City and Highway tests, with a 55% to 45% ratio respectively.
After the vehicle completes these tests, the vehicle will receive an EPA-rated driving range, as well as EPA-rated fuel efficiency. Please take a look at this official document for a complete guide and all-electric vehicle EPA-rated figures.
The Most Important Figure
The EPA produces a figure that says X miles. It will always be the ‘number’ people search for. That’s the driving range of the electric vehicle. The driving range is a measure of how far an electric car can go until the battery is depleted. There are three factors determining an electric car’s drive range:
The Car Specification
This includes the battery capacity, engine efficiency, total body weight, and temperature management system. For example, the Tesla Model 3 has a 54 kWh Lithium-Ion battery on the base model. It weighs 1.611kg, including the electric motor that weighs 46kg.
One of the most impactful factors for an EV is the temperature. Low temperatures make batteries suffer and perform worse. Another factor is the wind. Massive wind speeds will increase the vehicle’s drag, thus, wasting energy and reducing the driving range.
The driver also plays a part in determining the driving range. Low speeds will make the battery last longer because of less friction. High speeds will drain the battery faster because aerodynamic drag increases exponentially as the car goes more quickly. Alternating rapidly between low and high speeds will drain the battery fastest. Improper battery management, like not preheating your car before going out, can also impact battery health.
With the surge in the popularity of electric vehicles, consumers need a standardized measurement for an electric vehicle’s driving range. The United States Environmental Protection Agency (EPA) created the EPA-rated range. The EPA has several testing procedures that mimic closely to the real-life usage of an electric car. However, because there are so many environmental and user usage factors the EPA could not cover, it’s wise to assume the real driving range is slightly less than the EPA-rated range. The Tesla Model S Long Range Plus holds one of the highest EPA ratings, with 647km combined (55% city driving and 45% highway driving) and 111mpge fuel efficiency.