While hybrid cars have become increasingly common, many drivers are still unclear about the distinctions between the various types available. This guide from the automotive experts at cardiagxpert.com breaks down the four main types of hybrid vehicles, clarifying their unique characteristics and how they operate.
Mild Hybrids
Mild hybrid systems represent a recent advancement in hybrid technology. As the name suggests, these systems are not designed to power the vehicle solely on electricity. Instead, mild hybrids are engineered to support the gasoline engine, primarily during acceleration from a standstill, and to alleviate the engine’s load when powering auxiliary systems like air conditioning. Typically operating on 48-volt electrical systems, mild hybrids are self-charging. Their batteries are replenished through a combination of energy generated by the gasoline engine and kinetic energy recovered during braking, a process known as regenerative braking.
Mild hybrid technology is marketed under various names across different manufacturers. Notable examples include eAssist by General Motors, eTorque by Fiat/Chrysler, and EQ Boost by Mercedes-Benz.
Alt text: Diagram illustrating a mild hybrid system, highlighting the 48-volt battery, electric motor integrated with the gasoline engine, and regenerative braking components.
Full Hybrids
Similar to mild hybrids, full hybrid vehicles are equipped with both a gasoline engine and an electric motor. However, the electric component in a full hybrid is significantly more powerful and capable of undertaking a greater portion of the driving demands compared to a mild hybrid. Many full hybrids can operate solely on electric power for considerable distances, especially at lower speeds common in city driving. This electric-only capability often results in a higher City MPG rating than Highway MPG, a contrast to traditional gasoline vehicles where highway mileage is typically better.
Full hybrid powertrains are generally categorized into two main configurations: Parallel Hybrids and Series Hybrids.
Parallel Hybrids: In parallel hybrid systems, the vehicle can be propelled in three ways: directly by the gasoline engine, directly by the electric motor, or through the combined power of both systems working in tandem. This allows for flexible and efficient power delivery depending on driving conditions.
Series Hybrids: In contrast, series hybrids utilize the electric motor as the sole source of power to the wheels. The gasoline engine in a series hybrid functions exclusively as a generator, providing power to the electric motor and charging the battery. The gasoline engine never directly drives the wheels.
Modern hybrid technology has also led to the development of “series-parallel” hybrids. These advanced systems intelligently blend the characteristics of both series and parallel configurations. An onboard computer dynamically selects the most efficient operating mode based on real-time driving conditions, optimizing for both power and fuel economy.
Full hybrids, like their mild hybrid counterparts, recharge their battery systems through engine power and regenerative braking, ensuring continuous operation without the need for external charging.
Alt text: Schematic diagram of a series-parallel hybrid powertrain, showing the interaction between the gasoline engine, electric motor, generator, battery, and wheels in a full hybrid vehicle.
Plug-In Hybrids (PHEVs)
While the hybrid types discussed so far rely solely on internal systems for battery charging, plug-in hybrids introduce the capability of external charging. This is the defining characteristic of PHEVs – they can be connected to external charging sources, such as home chargers or public charging stations, to replenish their batteries. As a result of this external charging capability, plug-in hybrids typically offer a greater electric-only driving range compared to traditional full hybrids. Plug-in hybrids effectively bridge the gap between full hybrid vehicles and fully electric vehicles, offering a blend of electric driving for shorter commutes and gasoline engine backup for longer journeys.
Alt text: A plug-in hybrid electric vehicle being charged at a public charging station, illustrating the external charging capability of PHEVs.
Electric Vehicles with Range Extender Hybrids
Although fully electric vehicles (EVs) are not technically classified as hybrids, a specific category of EVs incorporates a small gasoline engine to extend their driving range when needed. Standard EVs rely solely on battery power and require recharging once depleted. Range extender hybrids address this limitation by utilizing a gasoline engine to either recharge the battery or directly power the electric motor, preventing drivers from being stranded due to depleted battery charge. The range extension provided by the gasoline engine can vary based on engine size, offering anywhere from a few dozen to several hundred additional miles of driving range. These range extenders provide an added layer of security and convenience for EV drivers, mitigating range anxiety.
Alt text: The BMW i3 Range Extender model showcasing its compact gasoline engine designed to extend the electric driving range, addressing range limitations in electric vehicles.
