Kinds of hybrid vehicles: differences between MHEVs, HEVs, and PHEVs

Talking about types of hybrid cars no longer means talking about a single technology. Today, several solutions coexist that combine thermal engines and electrical systems in very different ways. And that's where questions often arise: is a micro-hybrid (MHEV) really a hybrid? Can you plug in a regular hybrid (HEV)? Is a plug-in hybrid (PHEV) worth it if you don't have a charging point?

Understanding the differences between MHEVs, HEVs, and PHEVs is important because it affects consumption, daily use, purchase price, maintenance, and even the environmental label from your country's department of motor vehicles. In this guide, we review what each system offers and what is the best fit for each case.

What is a hybrid car and how is it different from a pure electric car?

Hybrid cars combine a combustion engine with one or more electric motors. The key is in how the work is distributed and in the capacity of the battery.

On the other hand, a pure electric runs on electricity alone. It has no gasoline or diesel engine, no need for conventional engine oil, and depends entirely on recharging your battery. If you want to learn more about how lubrication changes in these vehicles, you can read this guide on the types of lubricants for electric vehicles.

As for hybrids, a thermal engine is always present to a greater or lesser extent. Therefore, even if part of a trip can be done with the electric motor — or even in 100% electric mode in some cases — they still require proper mechanical maintenance, especially in with respect to engine oil and its possible breakdowns.

The three types of hybrid cars on the market

These are the three types of hybrid cars you'll find on the market, ordered from lowest to highest degree of electrification.

Micro-hybrid vehicles (MHEV)

MHEVs or microhybrids, also called mild hybrids, are the simplest form of electrification. They incorporate a small electrical system, usually 12 or 48 volts, which helps the combustion engine at specific times such as starting, gentle accelerations, or energy recovery after braking.

The key difference is that the electric motor does not move the car by itself. Their role is to assist, not propel independently. That is why, in real use, they are quite similar to a modern combustion engine vehicle, although with smoother operation and somewhat less consumption, especially in the city and in intermittent traffic.

They are a common option for those who want to use electrification without changing their habits too much. In Spain, MHEVs usually have the ECO label.

Conventional hybrid vehicles (HEV)

HEVs are conventional or non plug-in hybrids. Here, the vehicle's electrical system plays a much more prominent role. The battery's capacity is greater than that of a MHEV and the car can circulate in certain circumstances using only the electric motor (especially at low speed), in maneuvers, or in urban traffic.

The battery, however, cannot be plugged in for charging. It is charged with the energy recovered during braking and deceleration, and also with the support of the thermal engine when the system needs it. This is why we often talk about "self-charging" hybrids.

Its greatest strength is city driving. That's where they get the most out of their electrical side and where they usually achieve better consumption figures. HEVs also usually have an ECO label.

Plug-in hybrid vehicles (PHEVs)

PHEVs have a much larger battery, which can be charged by plugging the car into the power grid. This allows them to travel many more kilometers in electric mode than an HEV. This way, they can be driven multiple times as an electric on short journeys and as a hybrid on long journeys.

On paper they are the most versatile, but also the most dependent on actual use. A PHEV makes sense when charged frequently. If it is used almost always with the battery discharged, it drags more weight and can consume more than expected.

Direct comparison: MHEVs vs. HEVs vs. PHEVs

To compare them at a glance, this table summarizes the most important differences among these three major types of hybrid cars:

Price, real consumption, range in electric mode, and emissions labels

In terms of price, the order is usually clear: MHEVs are the cheapest, HEVs are in the middle, and PHEVs are the most expensive option. The difference does not only depend on the hybrid system, but also on the size of the battery, its power, and the equipment with which each brand sells a vehicle.

In real-life consumption, there is no single answer, because it depends very much on the use. In cities, HEVs are usually especially efficient because of how they use frequent braking and low-speed travel to their advantage. An MHEV reduces the expense of consumption somewhat as compared to a combustion equivalent, but the difference is usually more modest. Low viscosity oils, such as 0W-20, which are increasingly common in modern hybrids, also contribute to this efficiency. A PHEV can achieve very low consumption if it is recharged often and takes daily trips that fit within its electric mode range. Instead, if not plugged in regularly for charging, this advantage goes to waste.

When it comes to range in electric mode, the difference is also clear. MHEVs cannot drive in fully electric mode. HEVs can, but only for small stretches and under specific conditions. PHEVs, however, are designed to travel dozens of kilometers without using the thermal engine.

FAQs about types of hybrid cars

What types of hybrid cars are there?

There are three main kinds: micro-hybrids (MHEVs), conventional hybrids (HEVs), and plug-in hybrids (PHEVs). In MHEVs, a small electrical motor simply provides support to the combustion engine. HEVs can drive in fully electric mode in certain situations without the need for plug-in charging. PHEVs have a larger battery and must charge by plugging into the grid to travel more miles in electric mode.

Which is better, a PHEV or a MHEV?

It depends on the use. A PHEV can be better if you have somewhere to charge it and make daily trips that allow you to take advantage of its range in electric mode. In this scenario, it offers more capacity to reduce consumption and emissions on a day-to-day basis. An MHEV, on the other hand, is a better fit if you're looking for simplicity, a lower purchase price, and don't want to rely on recharging.

There is not one universal answer. Among the types of hybrid cars, the best one will be the one that best fits your routine.

Do non plug-in hybrid cars need to be plugged in?

No. HEVs do not need to plug in to the grid in any way to charge the battery. The battery is recharged while driving, thanks to energy recovery during braking and deceleration, and the management of the hybrid system itself.

What motor oil does a hybrid car need?

A hybrid car with a combustion engine needs an oil that meets the viscosity and specifications required by the manufacturer. But don't choose one just because the car is a hybrid. Always check the owner's manual first.

In hybrid vehicles, it is especially important to follow the manufacturer's instructions because the thermal engine can work with many starts and stops, cold operation phases, and frequent load changes.