Not All Hybrid Powertrains are Created Equal

From luxury cars to consumer cars, hybrid powertrains have been one of the most popular types of engine platforms to use among manufacturers in an effort to make cars more fuel-efficient and eco-friendly. But what is a hybrid powertrain and how do they work? There are actually a few different hybrid systems used in cars today, let’s take a quick look at these systems and their most popular applications.

All hybrid systems have the same basic components: an electric motor, an internal combustion engine, and a battery pack. The battery pack is a high-voltage unit that is separate from the 12-volt battery and gets recharged via regenerative braking and deceleration. Each hybrid system we’ll discuss here uses the same components, but just in different ways.

Parallel hybrid

This is the most common type of hybrid powertrain used. With the parallel hybrid system, the engine is used in conjunction with (or parallel to) the electric motor to power the wheels. The electric motor is used to start the car and propel it during light acceleration, while the gasoline engine comes on during higher speeds when more power is needed. Any extra power generated by the engine will be put back into the battery.

In cases when hard acceleration is needed, both the engine and the electric motor will power the car at the same time giving it more power and speed. This system can be found in popular makes like Toyota, Honda, Kia, Hyundai, Ford, and Nissan.  

2019 Toyota Prius Limited
2019 Toyota Prius Limited | Toyota

Series hybrid

In this hybrid system, the electric motor powers the wheels and the engine acts as a generator to recharge the battery. Driving a series hybrid is most akin to driving a pure electric car in that all of the acceleration and power comes from the electric motor only. One advantage to this system is that the vibration is minimal when the gasoline engine comes on, however, it can rev up during normal cruising (while charging the battery), which can be disconcerting. A popular model that uses this system is the BMW i3.

BMW i3

Plug-in hybrid

The plug-in hybrid is just like a conventional parallel hybrid, but it has a larger battery pack that must be charged externally, like an all-electric vehicle. The larger amount of stored electricity can then be used for all-electric driving (between 15 to 55 miles, depending on the car) before it switches over to the parallel hybrid system.

The main advantage of this system is that you could possibly do your daily commute completely on electric power and charge the car every night, furthering your fuel savings. Popular applications of this system are the Toyota Prius plug-in hybrid and Hyundai Ioniq plug-in.

Charging your electric vehicle battery
A plug of a charging station is connected | Silas Stein/picture alliance via Getty Images

Mild hybrids

All the other hybrids systems listed above are considered “full hybrid” systems in that the car can operate on the electric motor alone. A mild hybrid, on the other hand, is a hybrid power system in which the electric motor acts as a support for the gasoline engine when it comes to acceleration and upon startup.

The advantage of this system is that the electric motor adds power and improves fuel economy since the engine doesn’t have to work as hard. Popular current applications include the mild hybrid systems in various Audi models including the A6, A7, and Q8.

Audi A6

Save some fuel

These are the four main types of hybrids that you’ll find in various hybrid cars on the market today. While not all of them work in the same way, you’ll at least be able to figure out which one works best for you and your commute. Just note that your mileage, and fuel savings, may vary.