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Innovation, Hybrid cars

What is a mild hybrid? Is it worth buying a car with a Mild Hybrid system?

27 February 2023

In times of economic crisis and rising fuel prices, drivers are looking for the most economical vehicles possible, while manufacturers are looking for the best ways to efficiently comply with increasingly stringent emission limits. An interesting alternative to the still relatively expensive green modes of transportation are vehicles labeled with the acronym mHEV. What exactly is a mild hybrid? 

mHEV – what does it mean? 

You may come across the term mHEV when looking for information on different types of hybrid vehicles. The acronym is derived from Mild Hybrid Electric Vehicle. The so-called mild hybrid is one of three types of hybrid cars, which can also include full hybrid (HEV) and plug-in hybrid (PHEV). A mild hybrid is an intermediate solution between a traditional internal combustion engine and a full hybrid, so it features less complex electrical systems. For this reason, this solution, also often referred to as a "hybrid substitute," is much more affordable, and is also considered to have fewer breakdowns than traditional hybrid cars. It also allows you to enjoy the important advantage of this type of vehicle, which is the reliable operation of hybrid cars in winter. Energy from the battery allows the engine to run smoothly even at very low temperatures. The mild hybrid system can be used with both gasoline and diesel engines. The former is recommended mainly for city driving or short-distance trips, while the latter is recommended for longer routes and heavy loads requiring high torque, for example in mountainous areas. 

How does a mild hybrid work? 

The primary purpose of the mHEV is to reduce the consumption of traditional fuels and the emissions of the internal combustion engine. At the same time, due to the simpler design of the propulsion system, it is much cheaper to produce than full hybrids. The main component of the mild hybrid system is a small battery and an electric generator, which replaces the starters and alternators used in traditional vehicles and acts as a mini-motor. The kinetic energy accumulated by the generator during braking, such as when approaching an intersection or driving downhill, is used later to, among other things, help start the combustion engine, power on-board equipment or increase the torque of the combustion engine during rapid acceleration. The entire system is controlled by an on-board computer, which ensures efficient energy management. It is estimated that such a solution reduces the consumption of traditional fuel by about 5%, up to as much as 15%. Experts stress that the greatest benefits of the mild hybrid system can be felt especially during urban driving, which requires frequent stopping and starting. This is because this type of drive ensures a smoother ride, including when overtaking or merging into traffic. At the same time, due to the lower load on the combustion unit, nitrogen oxide emissions in some mild hybrids can be as much as 50-60% lower than in conventional combustion cars. 

Mild Hybrid technology – how does it differ from other types of hybrid drive?

Many people wonder whether a mild hybrid car is a full hybrid vehicle. Since mHEVs do not have a traditional electric motor, but rather a starter generator, they cannot be considered full hybrid vehicles, which generally have two "independent" types of propulsion. Unlike other types of hybrid propulsion, which allow you to travel a certain distance on an electric motor alone, for example, this type of system has only one mode – internal combustion assisted by an electric one. The electric generator, together with a small capacity battery, are not able to drive the car, but only support the internal combustion engine, relieving it at times of highest load and lowest efficiency. Thus, they reduce combustion and harmful emissions and increase the car's range. According to some manufacturers, such a system is said to provide up to 25% more torque, and at any rpm range. It is estimated that a car with such a drive solution gains about 10-20 horsepower. All this without the need for charging, as in the case of plug-in hybrids. The advantages of a mild hybrid also include the fact that, unlike a full hybrid, it has a low-voltage system that does not require specialized maintenance. 

Volvo Mild Hybrid, Skoda Mild Hybrid and other brands 

Today, cars with mild hybrid systems can be found in the range of many manufacturers. The forerunner of their application on a large scale was the Honda corporation, which decided to follow a completely different path of development than Toyota, which focused on hard hybrid technology. Over time, other manufacturers followed this direction as well, so today on the market you can see mild hybrid options from Hyundai, Suzuki or diesel-based KIA and Mercedes mild hybrid solutions. As for European manufacturers, mild hybrids are relatively widespread in the offers of the Volvo or Volkswagen groups, among others. Such a drive has been applied in the Volkswagen Golf, for example, with a 48-volt installation, a compact lithium-ion battery that fits under the passenger seat and an electric generator that acts as an alternator and starter. A similar solution can be found in the popular Skoda Octavia as well as in Audi's luxury car models. 

Automotive components for mHEV made of innovative materials 

Since electric batteries take up much less space in mHEVs than in traditional hybrid or electric vehicles, car designers gain more opportunities to customize the interior of the passenger compartment and luggage section. At the same time, the car's design must be as light as possible to minimize the fuel consumption of the internal combustion engine. This is where innovative foamed plastics come to the rescue. EPP foamed polypropylene allows the economic production of various types of car parts, which feature up to half the weight of their counterparts made of traditional materials. Seats, floor fillings or door mats produced with it simultaneously meet the most stringent requirements for durability and safety. The cellular material is filled in 95% by air, is characterized by extraordinary resistance to any mechanical damage, and also has shape memory. After a momentary deformation, it returns to its previous form, so it can continue to fulfill its function. This is why EPP components are popularly used as damping elements in modern bumpers. Meanwhile, the foam's excellent properties related to its thermal, acoustic and electrical insulation have led car designers to reach for it in such modern applications as the manufacture of battery packs for electric cars or even protective domes for hydrogen tanks. 

Main photo: newsroom.toyota.eu

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