Extended Range Electric Vehicles (EREVs): A Comprehensive Guide to Their Benefits and Challenges

Choosing an electric vehicle can be a complex decision. Between brand options, features, and assessing value for money, the process can be overwhelming. Additionally, charging infrastructure plays a crucial role: Are public chargers accessible where you live? Can you charge at home? If both answers are no, could a Plug-in Hybrid (PH) be a solution? Or what about an Extended Range Electric Vehicle (EREV or ER)?

Although both ERs and PHs feature electric motors powered by batteries, their designs diverge significantly. An ER employs a combustion engine solely as a generator; it is disconnected from the drivetrain. Typically gasoline-powered, this engine charges the battery when it runs low.

ERs have built-in generators, eliminating the need for large battery packs. Their batteries are usually no larger than 45 kWh but still offer a respectable electric-only driving range, often up to 200 kilometers. When the battery depletes, drivers can either rely on the onboard generator or recharge at a DC fast charger.

This dual capability enables ERs to self-recharge, providing peace of mind for longer trips or unexpected situations when charging stations are unavailable. For many drivers, a 200 km electric range covers most daily needs.

Both PHs and ERs incorporate combustion engines, but their key difference lies in drivetrain connection. ERs disconnect the combustion engine from the wheels, removing the need for complex transmissions and allowing the engine to run at a constant, fuel-efficient speed.

ERs tend to deliver higher power than PHs. It’s common to find ERs with electric outputs as high as 300 kW, benefiting from the instant torque of electric motors for a more engaging driving experience. Additionally, ERs usually offer greater electric-only range and support DC fast charging.

However, these vehicles are mostly available as larger SUVs or crossovers, reflecting manufacturers’ current market focus. Whether this trend will shift depends on wider adoption of ER technology. Some early ER models are less fuel efficient than cutting-edge PHs, and charging the battery via an onboard generator can cost more than using public chargers.

Designed to circumvent battery charging limitations, ERs address a major barrier to electric vehicle adoption: insufficient charging infrastructure. They offer a “bridge” technology, enabling electric driving for up to 1,200 km by combining battery and generator use.

While charging infrastructure is improving, recharging times remain a challenge. For example, emergency vehicles cannot afford extended charging breaks. ERs fit this use case well — primarily using battery power, with the combustion engine activating only as a backup without sacrificing performance.

Cost-wise, ERs are generally more affordable than equivalent pure electric vehicles because their batteries are smaller. Smaller batteries reduce manufacturing costs and ease pressure on scarce lithium supplies, especially relevant as sodium-ion alternatives are still emerging.

Nonetheless, there are drawbacks. When unused, the combustion engine adds weight without contributing to propulsion — often about 300 kg of idle components over most of the vehicle’s life. Moreover, the combustion engine requires regular maintenance, undermining some of the low upkeep benefits of pure electric cars.

Manufacturing compact ERs is complex and expensive, making them more viable in larger vehicles that demand bigger batteries. The engine and generator also occupy space, reducing available storage areas such as the front trunk, and may affect safety ratings and reliability compared to fully electric models.

Which ERs are available today?

ERs are particularly popular in China, where the market segment is rapidly growing. Outside China, options are limited. The Mazda MX-30 R-EV, featuring a rotary engine as a range extender, is anticipated but not yet available broadly. Another notable model is the LEVC TX, the London Taxi, which offers passenger and van versions, built by Geely using Volvo parts. Known for good build quality, it comfortably seats eight passengers.

The AITO M5 is one of China’s early ER entrants. Its 1.5-liter turbocharged 4-cylinder engine with 123 hp serves only as a generator. A 40 kWh battery provides a 140 km electric range, after which the range extender enables over 1,000 km total (NEDC). Available in both 2WD and AWD, the AWD variant delivers 315 kW and 720 Nm, accelerating from 0 to 100 km/h in just 4.4 seconds.

Theoretical fuel consumption stands at 6.5 liters per 100 km based on claimed range and fuel tank capacity.

Li Auto exclusively produces ER vehicles. Its lineup includes the Li L9, Li L8, and Li L7. The Li L8 and L7 feature 42 kWh batteries paired with 1.5-liter gasoline generators, boasting a total range of 1,315 km and an electric range of approximately 210 km.

The larger Li L9 uses the same generator but a slightly bigger 44.5 kWh battery, delivering 180 km electric range. Despite size differences, both Li L9 and L8 claim identical 1,315 km total range. The Li L9 carries a 65-liter fuel tank, yielding an average fuel consumption of 5.7 liters per 100 km—impressive for a vehicle larger than the Mercedes EQS SUV.

Voyah Free is another Chinese ER available in battery-only and ER variants. It uses a 1.5-liter turbocharged 4-cylinder engine with a 33 kWh battery. Dual electric motors generate 500 kW (671 hp) and 1,000 Nm torque, achieving 0–100 km/h in 4.6 seconds with a combined range of 860 km.

The 56-liter fuel tank supports approximately 700 km of range with the generator. Estimated fuel consumption is around 8 liters per 100 km. The electric-only range is inferred to be around 160 km.

BYD offers a broad ER model lineup, including the Song Plus, Tang, and Han, with the DM-i (Dual Mode) trim. These use a 1.5-liter engine powering batteries between 10 and 21.5 kWh, delivering over 1,000 km combined range.

The BYD Han DM-i variant covers up to 242 km electrically and 1,158 km using the range extender. With a 50-liter fuel tank, its average consumption registers at 4.3 liters per 100 km.

Final Assessment

Extended Range Electric Vehicles are not a new concept. Early 20th-century electric cars relied on gasoline generators due to limited battery technology. More recently, the Chevrolet Volt and BMW i3 REx incorporated similar concepts but had limited sales and are now discontinued. The Volt notably allowed the engine to drive wheels directly, while the i3’s fuel tank served mainly as an emergency backup.

Whether ERs will gain wider adoption depends on the growth of charging infrastructure and development of affordable batteries. As long as these challenges persist, ERs will continue to provide a practical transitional solution. While they do not resolve long-term emissions issues, they offer a vital bridge between conventional and fully electric mobility.