Understanding Extended Range Electric Vehicles (EREVs): Features and Benefits

Purchasing an electric car can be challenging. With numerous brands and options available, identifying the best value can be daunting. Additionally, charging infrastructure is a crucial consideration—are there sufficient public chargers in your area? Can you charge at home? If the answers to these questions are negative, could a Plug-in Hybrid (PH) or an Extended Range Electric Vehicle (EREV) be viable alternatives?

An EREV shares similarities with a PH, as both utilize electric motors and batteries. However, the key distinction lies in their operation: the EREV employs a combustion engine solely as a generator, meaning there is no direct link between the engine and the drivetrain. Typically powered by gasoline, the generator's primary role is to recharge the batteries when they are low.

Equipped with a built-in charger, an EREV does not require a large battery; they usually feature battery packs of no more than 45 kWh. Despite this, they still provide a respectable electric-only driving range, often allowing some models to travel up to 200 km. When battery charge is low, drivers can either activate the generator or stop at a DC charger for a speedy recharge.

This capability is intriguing, as it means the EREV can recharge itself if DC or AC chargers are unavailable. A driving range of 200 km meets the daily needs of many drivers, while the onboard generator ensures additional peace of mind for longer trips or unexpected detours.

How do PHs and EREVs compare, particularly when both have combustion engines? The EREV represents a more advanced version of the PH. Disconnecting the gasoline engine from the drivetrain eliminates the need for complex gearboxes and allows the engine to operate consistently at its optimal speed, further enhancing fuel efficiency.

ERs typically offer greater power than PHs, often featuring up to 300 kW of pure electric power. Their electric-only powertrain and immediate torque contribute to a more enjoyable driving experience. Additionally, EREVs provide a more extensive electric-only range than PHs and can utilize DC fast chargers.

However, there are drawbacks. Currently, EREVs are primarily available as larger SUVs and crossovers, as manufacturers focus on this segment. It remains uncertain if this trend will shift; EREVs would need to gain widespread popularity first. Another potential downside is that some early EREVs are less fuel-efficient than the latest PHs, and recharging the battery via an onboard generator can be more costly than using a DC or AC charger.

These vehicles are designed to theoretically offer electric driving without the restrictions of battery charging infrastructure. The main barrier to widespread electric vehicle adoption is the lack of charging options. EREVs eliminate this hurdle, effectively providing an interim solution with electric driving capabilities for distances up to 1,200 km.

While charging infrastructure is continually improving, it will take time for universal availability. During this transition, the time required to recharge a vehicle can pose challenges. For example, consider an electric emergency vehicle that might need to halt for thirty minutes—a significant drawback. EREVs are well-suited for such use, as they predominantly operate on battery power, with the combustion engine serving as a backup without affecting performance.

Price-wise, EREVs are generally more affordable than their electric-only counterparts, mainly due to their smaller batteries. This reduced battery size not only results in lower vehicle costs but also an increase in available vehicles. With lithium supply constraints and sodium-ion batteries still emerging on the market, it may take several more years before battery prices decrease and their availability increases.

Although they offer advantages, EREVs are not without flaws. The combustion engine, when unused, contributes unnecessary weight to the vehicle, and often, onboard generators operate less than 10% of the time—leaving up to 300 kg of inactive components. Additionally, while electric vehicles typically incur lower maintenance costs, EREVs require regular checks for their combustion engines, similar to traditional cars, posing potential reliability concerns.

Designing a small, city-friendly electric vehicle is relatively straightforward, while constructing a compact EREV is more complex and can be costlier than a pure electric vehicle. EREVs can be more sensible in larger vehicles, which require bigger batteries.

Finally, the gasoline engine requires additional space, which can reduce trunk capacity. Moreover, safety implications, accident ratings, and overall reliability may suffer in comparison to fully electric vehicles.

Which One to Choose?

If you believe that an EREV could be the solution to your driving needs, it is essential to recognize that these vehicles are particularly popular in China, where the EREV segment is rapidly growing. In contrast, options in other parts of the world remain limited, with notable upcoming models such as the Mazda MX-30 REx, which is set to feature a rotary engine. While exciting for enthusiasts, this could lead to complications for others.

Another available option is the LC TX—the London Taxi—offered in passenger and van versions. This vehicle has several advantages, including its construction by Geely with many Volvo components. It boasts good quality and satisfactory performance, although the unique nature of a taxi might not appeal to everyone, as it tends to carry multiple passengers at once, providing significant legroom in the rear seats.

The AITO M5, one of the first EREVs on the Chinese market, features a 1.5-liter turbocharged four-cylinder engine producing 123 hp. Notably, this power output does not contribute to the vehicle's total output, as it does not drive the wheels. The M5 includes a 40 kWh battery, providing a 140 km electric-only range before the extender engages, totaling over 1,000 km of range (NEDC). It is available in both 2WD and AWD configurations, the latter boasting two electric motors with a combined output of 315 kW and impressive torque of 720 Nm, allowing acceleration from 0 to 100 km/h in just 4.4 seconds.

The claimed 1,000 km range indicates that the M5 uses approximately 56 liters of fuel to cover 860 km, translating to a theoretical consumption rate of 6.5 l/100 km.

The Li Auto lineup exclusively features EREVs. The latest model, the Li L9, replaces the previous Li ONE. Other models include the Li L8 and Li L7, both equipped with a 42 kWh battery alongside a 1.5-liter gasoline generator. According to the manufacturer, the L8 offers a total range of 1,315 km, with 210 km available on battery power alone.

The larger L9, featuring a slightly increased battery capacity of 44.5 kWh, provides a lower electric range of 180 km due to the vehicle's size. Remarkably, both models claim the same total range of 1,315 km. Though details about the forthcoming Li L7 remain scarce, it will likely use the same generator with a comparable battery capacity of around 40 kWh.

The Li L9 has a 65-liter fuel tank and can cover 1,135 km on that fuel, considering its 180 km electric range, resulting in an average consumption rate of 5.7 l/100 km—not bad for a vehicle larger than the Mercedes EQS SUV.

Voyah Free is another Chinese EREV that also offers a battery-only version. In its EREV configuration, it features a 1.5-liter turbocharged four-cylinder engine coupled with a 33 kWh battery. The vehicle employs two electric motors, producing a combined peak output of 500 kW (671 hp) and torque of 1,000 Nm. Its stated combined range is 860 km (530 miles), with acceleration from 0 to 100 km/h in 4.6 seconds.

The Voyah Free is equipped with a 56-liter fuel tank, but the manufacturer's claims about its electric-only range remain unconfirmed. Assuming the 33 kWh battery provides a range of no more than 160 km, this would leave approximately 700 km covered using the range extender, resulting in a fuel consumption rate of 8 l/100 km.

BYD features a broad range of EREVs, with popular models including the Song Plus, Tang, and Han. These vehicles are classified under the DM-i (Dual Mode) trim, featuring a 1.5-liter engine paired with either a 10 or 21.5 kWh battery. All three models can reportedly achieve a total combined driving range exceeding 1,000 km.

The BYD Han DM-i, equipped with the larger battery, can travel up to 242 km in electric-only mode, with an additional 1,158 km utilizing the range extender. With a 50-liter fuel tank, it achieves an average consumption rate of 4.3 l/100 km.

Final Thoughts

EREVs are not a completely new concept; this technology mirrors the early 20th-century deployment of electric vehicles that relied on gasoline generators due to limited battery technology. Similarly, contemporary examples like the Chevrolet Volt and BMW i3 REx were technically EREVs, although they did not achieve significant sales and are no longer produced. The Volt cleverly drove its wheels through the clutch system, while the i3 REx's fuel reliance was only meant for emergency use.

Will the EREV trend gain traction? Much hinges on the speed of advancements in charging infrastructure and the development of affordable batteries—two areas currently impeding progress. As long as these challenges remain, EREVs could serve as an effective interim solution. With governments worldwide committing to ambitious targets, these vehicles provide a potential bridge from current technology to a more sustainable future.