What is a mild hybrid car (MHEV)?

Many carmakers now offer models equipped with mild hybrid technology, but what exactly does that mean and how does it work? Read on to find out more.

Not long ago, hybrid technology was limited to two types: “self-charging” hybrids, which can drive short distances on electric power without a plug, and plug-in hybrids, which have larger batteries but needed to be plugged in to recharge. Now, there’s the option to buy a mild hybrid.

You might have heard the term ‘mild hybrid’ before and felt a bit perplexed about what that is. Don’t fret – this handy guide is here to explain its meaning and how it works.

What is a mild hybrid car?

A mild hybrid (MHEV) pairs a small electric motor and battery with a conventional petrol or diesel engine to improve fuel efficiency and cut emissions. However, unlike full hybrids, it can’t run on electric power alone.

How does a mild hybrid work?

Mild hybrids use a small electric motor and a 48-volt battery to support a regular petrol or diesel engine. The motor boosts acceleration and helps recover energy during braking, storing it in the battery. This reduces strain on the engine, improves performance, and enhances fuel efficiency.

What are the advantages and disadvantages of a mild hybrid?

There are numerous pros and cons to a mild hybrid – some of which could tempt you towards or away from them.

Advantages to a mild hybrid car

• Feels like driving a regular petrol or diesel car
• No need to plug in, unlike plug-in hybrids
• They’re typically more affordable than full or plug-in hybrids
• Improved fuel economy and lower CO2 emissions, reducing fuel costs and Vehicle Excise Duty
• The technology works with manual and automatic, and petrol and diesel models

Disadvantages to a mild hybrid car

• Cannot drive on electric power alone
• Produce more tailpipe emissions than full or plug-in hybrids
• Less fuel-efficient compared to full hybrids and plug-in hybrids, especially in urban driving

Mild hybrid vs full hybrid: what’s the difference?

The key difference between mild and full hybrid cars is their electric capabilities. Mild hybrids use an electric motor to support the engine, while full hybrids can operate on electric power alone for short distances.

Mild hybrid vs plug-in hybrid: what’s the difference?

Mild hybrids cannot run solely on electric power and their batteries are charged by the engine and regenerative braking. Meanwhile, plug-in hybrids can be charged externally and can travel a significant distance on electric power alone.

Are mild hybrids worth it?

If you’d prefer to stick to a conventional combustion-engined car but want a little extra efficiency, a mild hybrid could be the right choice for you.

If you’re looking for something to cover electric-only driving reasonably often though, a conventional hybrid or plug-in hybrid serves as a better halfway house to a fully electric vehicle. Keep in mind these typically cost more than mild-hybrid equivalents, though.

Mild hybrid car (MHEV) FAQs

Can a mild hybrid run on electricity only?

A mild hybrid car cannot cover any notable distance on electricity alone. Typically, they can allow the engine to be off longer when coming to a stop and assist in pulling away.

Do mild hybrids charge while driving?

Mild hybrid systems recover power from the engine, meaning you won’t need to charge one.

What happens if you don’t charge a mild hybrid?

Mild hybrid systems recover power from the engine, meaning it’ll keep itself charged. You won’t need to even think about it.

How much does a mild hybrid cost to buy?

Mild hybrid cars may have a small premium over regular combustion-engined equivalents, but tend to be cheaper than hybrid models.

How much does a mild hybrid cost to run?

In theory, a mild hybrid car should be slightly cheaper to run than a conventional pure combustion engined equivalent. Don’t expect huge drops in fuel costs, though.

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