Mild hybrids (MHEV) (also known as smart hybrids, power-assist hybrids, battery-assisted hybrid vehicles or BAHVs) are generally

car A car, or an automobile, is a motor vehicle with wheels. Most definitions of cars state that they run primarily on roads, seat one to eight people, have four wheels, and mainly transport people rather than cargo. There are around one billio ...

s with an

internal combustion engine An internal combustion engine (ICE or IC engine) is a heat engine in which the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal comb ...

(ICE) equipped with a minimally extended battery and an auxiliary electric combined motor and generator in a

parallel hybrid Hybrid vehicle drivetrains transmit power to the driving wheels for hybrid vehicles. A hybrid vehicle has multiple forms of motive power, and can come in many configurations. For example, a hybrid may receive its energy by burning gasoline, but swi ...

configuration that is only enough for an electric-only mode of propulsion at slow speed and allows the engine to be stopped whenever the car is coasting, braking, or stopped, and then restarted once power is required again. Mild hybrids may employ regenerative braking and some level of power assist to the internal combustion engine.

Overview

The mild hybrid's

electric motor An electric motor is a machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electric current in a electromagnetic coil, wire winding to gene ...

provides greater efficiency through the use of a single device that is essentially an integrated starter/alternator sometimes known as a generator-motor unit. A typical mild-hybrid setup uses a belt-powered generator-motor unit driven off the engine to supply power to a small battery. The generator is also powered through regenerative braking, enabling power that would otherwise be dissipated as heat to be recaptured and recovered for use in powering the vehicle. The small power assist generated by mild-hybrid systems can help supplement the internal combustion engine in low-speed situations or handle the demands of engine start/stop functionality. Vehicles equipped with a mild-hybrid system typically see anywhere from a improvement in fuel economy relative to comparable models without the technology – a saving of 2 to 8 percent.

Dual mild hybrids

These contain two different energy recovery systems. The Mercedes-Benz C-Class (W206), Mercedes-AMG SL 43 (R232), the Mercedes-AMG CLE 53, the petrol Mercedes C254/X254, and the Porsche 911 Carrera GTS T-Hybrid have an electrically-assisted turbocharger/ MGU-H.

Criticisms

There is doubt on whether mild hybrids should be classified as hybrid or have EV (electric vehicle) in their MHEV abbreviation as they cannot be powered only by electricity at any time. Their emissions reduction is often so low that the impact on environment is negligible and may be seen as greenwashing.

Examples

General Motors

General Motors General Motors Company (GM) is an American Multinational corporation, multinational Automotive industry, automotive manufacturing company headquartered in Detroit, Michigan, United States. The company is most known for owning and manufacturing f ...

mild hybrids, including the Parallel Hybrid Truck (PHT) and numerous cars and SUVs equipped with the belt alternator starter ( BAS) hybrid system, often use a 36- to 48-volt system to supply the power needed for the startup motor, as well as a source of power to compensate for the increasing number of electronic accessories on modern vehicles. GM's belt alternator starter (BAS) mild hybrid system uses a belt drive to start the

(ICE) through its motor–generator unit (MGU); then once started, the engine drives the 14.5 kW motor-generator to charge the batteries. The BAS hybrid system also utilizes regenerative braking to replenish the system's 36 V battery and can provide moderate levels of power assist. According to the EPA, a 2009 Saturn Vue Greenline equipped with the BAS hybrid system delivers a 27% improvement in combined fuel economy over the non-hybrid version (FWD 4cyl).

Others

During the 2008 Olympic Games in Beijing in August, Chinese automobile manufacturer Chang'an Motors supplied a number of hybrid-drive cars as taxis for the athletes and spectators. The power electronics for the "mild hybrid" drive was supplied by

Infineon Infineon Semiconductor solutions is the largest microcontroller manufacturer in the world, as well as Germany's largest semiconductor manufacturer. It is also the leading automotive semiconductor manufacturer globally. Infineon had roughly 58,0 ...

Toyota is a Japanese Multinational corporation, multinational Automotive industry, automotive manufacturer headquartered in Toyota City, Aichi, Japan. It was founded by Kiichiro Toyoda and incorporated on August 28, 1937. Toyota is the List of manuf ...

sold mild hybrid versions of the

Toyota Crown The is an automobile which has been produced by Toyota in Japan since 1955. It is primarily a line of mid-size luxury cars that is marketed as an upmarket offering in the Toyota lineup. In North America, the first through fourth generation ...

executive sedan between 2001 and 2003 and the mid-size Crown Sedan between 2002 and 2008 in the Japanese domestic market. MINI and

BMW Bayerische Motoren Werke AG, trading as BMW Group (commonly abbreviated to BMW (), sometimes anglicised as Bavarian Motor Works), is a German multinational manufacturer of vehicles and motorcycles headquartered in Munich, Bavaria, Germany. Th ...

have start and stop, and some with regenerative braking, in all of their vehicles sold in Europe running 4-cylinder engines with manual transmissions.

Citroën Citroën ()The double-dot diacritic over the 'e' is a diaeresis () indicating the two vowels are sounded separately, and not as a diphthong. is a French automobile brand. The "Automobiles Citroën" manufacturing company was founded on 4 June 19 ...

proposes a stop and start system on its C2 and C3 models. The concept-car ''C5 Airscape'' has an improved version of that, adding regenerative braking and traction assistance functionalities, and ultracapacitors for energy buffering. In 2004 VW brought two mild hybrid concept cars to Shanghai for the Challenge Bibendum. Most hybrids use gasoline engines, but some use diesel engines, such as the Hyundai 1.6. In 2021 Land Rover started selling the Range Rover Sport D350, which runs on the 3.0-litre D300 Ingenium diesel engine. The Genesis G90 and Genesis GV80 Coupe offer mild hybrid options with an electric supercharger.

References

{{Reflist Hybrid powertrain Hybrid vehicles de:Hybridelektrokraftfahrzeug#Mild-Hybrid