Mild hybrid vs full hybrid vs plug-in: Differences, pros & cons

A hybrid car combines a petrol or diesel engine with an electric motor. This setup is more eco-friendly than conventional petrol or diesel cars because it uses less fuel and produces much lower CO2 emissions.

You have several options here: mild hybrids (MHEVs) that use a small generator to harness power when decelerating to assist the engine when speeding up, self-charging hybrid cars (HEVs) that use both the engine and electric motor to drive and recharge, and plug-in hybrids (PHEVs) that you can charge from an external source.

It might be a bit tricky to grasp all the differences at once, so let’s take a closer look at each type to make things clearer.

What are the different types of hybrid cars?

Here’s a breakdown of what each hybrid option offers and why you might want to consider one:

What is a mild hybrid (MHEV)?

A mild hybrid has a small electric generator instead of a traditional starter motor and alternator. This raises fuel economy and minimises CO2 emissions by using the motor to help with tasks like quick acceleration and resuming after a pause stop. It also collects energy when you brake and stores it in the lithium-ion battery to give extra electric support when needed.

What are the advantages of a mild hybrid car?

• They produce less pollution than regular petrol and diesel cars, which is better for the environment.
• You don’t need to connect a mild hybrid to a power source. It recharges itself using the conventional engine and braking system.
• The battery pack helps the engine perform better and gives you quicker acceleration.

What are the disadvantages of a mild hybrid car?

• They emit more pollutants than full hybrids because they can’t drive using only electric power.
• The engine runs constantly, so it’s not as fuel-efficient as cars that can drive on electric power alone.
• They don’t save as much fuel as plug-in hybrid cars do.

What is a self-charging/full hybrid (HEV)?

A hybrid car offers a combination of a petrol or diesel engine with an electric motor. Self-charging hybrid cars use the engine to recharge the battery, which makes them work a lot like regular cars and eases the shift to electric driving. The petrol engine and the electric motor work together, so you don’t have to worry about running out of battery.

What are the advantages of a full hybrid car?

• They can travel on electric power alone at slow speeds, which is perfect for stop-and-go traffic in towns and cities.
• They consume less fuel than standard cars by switching between electric energy and the engine.
• Full hybrids recharge themselves automatically while you drive, so you don’t have to worry about plugging in.

What are the disadvantages of a full hybrid car?

• The benefits of hybrid cars are less pronounced on longer journeys
• They usually cost more to buy than regular cars or mild hybrids.
• If the battery needs to be replaced, it can be quite costly.
• Full hybrids don’t come with manual gearboxes, so if you prefer driving a manual car, your choices are limited.

What is a plug-in hybrid (PHEV)?

As the name implies, a plug-in hybrid is a type of hybrid car that you charge using an external power source. The batteries are larger than the ones in regular hybrid cars, so they run mainly on electric power. This means you can drive on pure electricity for shorter trips and use petrol only when the battery is low on longer journeys.

But if the battery is depleted, the internal combustion engine will automatically switch on.

What are the advantages of a plug-in hybrid car?

• You can use the motor for short journeys and switch to engine power for longer trips, so you have options.
• You can drive without producing emissions during your daily commute.
• Since they have an engine as a backup, you don’t have to stress about running out of battery on longer journeys.

What are the disadvantages of a plug-in hybrid car?

• You need to charge the battery often, which can be inconvenient if you don’t have a charger at home or nearby.
• The battery adds extra weight, which reduces how efficiently the car uses fuel.
• When driving without using the electric motors, the engine won’t be as powerful as some other cars.
• The battery takes up space and affects the boot and legroom.

Comparing hybrid types: Hybrid vs. Plug-in Hybrid vs. Mild Hybrid

The main difference between hybrids, mild hybrids, and plug-in hybrids comes down to how they are powered. Plug-in hybrid cars need to be plugged into a charging point or home charger to recharge their batteries. Self-charging hybrid cars charge their batteries while you’re driving, using the engine to power it. Mild hybrid cars don’t require any plugging in; they use a battery that gets charged by the engine and through regenerative braking, which captures energy when you’re slowing down.

Hybrid cars are more efficient than traditional petrol or diesel ones because they get energy back with regenerative braking, which is wasted in regular vehicles. With plug-in hybrids, you’ll need to recharge the battery when it gets low, much like charging your phone. If there’s no charging station nearby, the car’s traditional combustion engine will take over, so you won’t be stranded.

In terms of energy usage, mild hybrids can’t run on electric power alone; their electric motors just help the engine. Regular hybrids use both the engine and the electric motor to move the car. Plug-in hybrid cars mostly rely on their electric motors and turn on the engine only when the battery is dead.

Comparison table for hybrid types

We’ve covered most things at this point, but to simplify, let’s look at the main characteristics and benefits of each hybrid type:

Tax breaks and financial benefits

For hybrid cars registered after March 1, 2001, road tax is based on CO2 emissions. Since hybrids emit less CO2, they have lower road tax and save you around 20%-25% compared to regular cars.

Company car tax is based on the car’s value and CO2 emissions. Hybrids usually have lower tax rates because of their reduced emissions.

Which type of hybrid is right for me?

When it comes to buying a hybrid, here’s some guidance for choosing the right type for you:

• Mild hybrids — These are good if you want extra fuel savings without needing to plug in. Mild hybrid cars are great for everyday driving and are usually cheaper.
• Full hybrids — These are a great idea if you want better fuel efficiency and don’t mind a bit more technology. They’re ideal for city driving and longer trips.
• Plug-in hybrid cars — Choose these if you can charge your car regularly and want to use electric power more often. They’re ideal if you have a short commute and easy access to charging.

Think about how you drive, if you have a place to charge your car, and how much you’re willing to spend.

Could I just go fully electric instead?

It’s definitely possible! Electric cars are pricier than hybrids, but if you’re already driving mostly on electric power, it might be worth making the switch.

Choosing an all-electric vehicle helps you save more on running costs and completely eliminate tailpipe emissions. You could also make up the higher initial cost more quickly.

One common concern is charging during long trips. Stories of people getting stuck at malfunctioning chargers or left on the roadside can be off-putting. While the UK’s charging network is still developing and some charging points have issues, many drivers manage well — especially those with access to networks like Tesla’s Superchargers. A bit of careful planning makes long journeys in an electric car quite practical.

Final words

If you mostly drive in the city or on short trips, any of the hybrids we talked about would work well for you. However, if you go on long trips or drive on the motorway, a full or plug-in hybrid might not be the best choice. In that case, if you still want a hybrid, a mild hybrid could be a better fit.