What is a mild hybrid car?

What is a mild hybrid car?

If you’re on the hunt for a new car, you’ve probably realised the list of options for car type is getting longer. Electric and hybrid cars are becoming a bigger and bigger part of the car market, and nestled in the middle of it all are mild hybrid cars.

If you’re considering buying a new car, you might want to check out our blog ‘Is it better to lease or finance a car in the UK?

Mild hybrid cars are a pretty simple concept, but it can still be a bit confusing. So, we’ve put together this blog to make sure you know what a mild hybrid car is, and why people are buying them.

What is a mild hybrid car?

Basically, a mild hybrid car is a normal petrol or diesel car with an added small (usually 48V) battery and an electric motor. Generally, this battery will power electrical parts of the car like the onboard computer, air conditioning and radio. By using a battery, the engine has to power fewer parts of the car, so you use less fuel.

In some cases, the battery in a mild hybrid car can also give the engine a small boost when you accelerate from a low speed. If you put your foot down to gain speed quickly in a conventional car, this can use a lot of fuel and produce a lot of emissions. In a mild hybrid car, that power is coming from electricity instead of fuel, so the emissions aren’t as high.

The exact way a mild hybrid car uses its battery power can vary from car to car. Some mild hybrid cars are able to shut the engine down entirely for a short time whilst coasting, helping you save fuel. Other mild hybrid cars essentially use the battery as an extra power unit, with some sports cars in recent years using the extra battery as a booster to help the car accelerate faster.

So, what counts as a mild hybrid can vary quite a bit depending on how the manufacturer interprets the definition.

How is a mild hybrid different from a full hybrid?

If you’re thinking about buying yourself a new car, there are a few key differences between mild hybrids and full hybrids that might be worth noting.

  • Mild hybrids can’t run on just the battery - Full hybrids are built to switch between the engine and the battery as they need, with the main objective to run on the battery as much of the time as possible. Mild hybrids can’t do this. They run on the engine and the battery just helps to relieve some of the stress.
  • You don’t need to charge a mild hybrid - Mild hybrid cars charge their batteries when you brake, so the battery doesn’t need to be charged up before you set off. A lot of full hybrids don’t need to be charged either, but their batteries usually drain faster over longer distances. So, if you’re taking a long journey on the motorway in a full hybrid, they'll probably need to start burning fuel fairly soon anyway.
  • Mild hybrids can have manual transmission - Hybrid and electric cars are all automatic at the moment, as so much of the internal workings of the car rely on battery power. Mild hybrid cars can still be manual because they’re basically conventional cars with an added battery.

Mild hybrid cars are often seen as a transition between conventional petrol and diesel cars and hybrid or electric cars. They provide some of the benefits of a battery, but the driving experience should be pretty close to what you’re used to in a normal car.

If you’re trying to decide between a petrol or diesel car, it might be worth checking out our blog ‘Should I buy a diesel car?

Should I buy a mild hybrid?

The question of whether you should actually buy a mild hybrid really depends on how you feel about your car and what you’re looking for. As the country continues to move towards electric and hybrid cars, you might find that a mild hybrid car can give you an easier transition.

Here are a few things to consider if you’re thinking about buying a mild hybrid car:

Fuel economy

Using a battery to help with the engine power means less demand on the engine, so you use less fuel to do the same job. With your engine not having to work as hard, you will likely burn fuel more efficiently and could even see yourself driving longer distances on the same tank of fuel.


Generally speaking, a mild hybrid of comparable size and power will be more affordable than the equivalent hybrid or electric car, at least at the moment. It’s looking like things are due to change, but it’s a slow-moving revolution towards electric cars at the moment. Also, car repair centres tend to be geared towards conventional cars, and mechanics who can fix electric and hybrid cars are still seen as specialists. With mild hybrid cars being essentially conventional cars with an extra battery, you’re a bit more likely to be able to get your car fixed affordably, compared with an electric or full hybrid car.


With mild hybrid cars working much like a standard car, there’s no reason to think that you wouldn’t be able to take the same journeys in one as you would normally. Particularly over long distances, the fuel-saving aspect of a mild hybrid car might actually help you go further. Unlike electric cars, there’s no chance that a flat battery is going to stop you in your tracks, and you can just refill the car with petrol or diesel as it needs.

If you’re wondering how long a battery should last in the long run, you can check out our blog ‘How long should a car battery last in the UK?’


Mild hybrid cars are, for the most part, not as great for the environment as a full hybrid or an electric car, but they can be seen as a step in the right direction. They probably won’t save you money on a congestion charge because they don’t count as zero-emission, but a mild hybrid car does at least save some fuel.


With the battery helping the engine at lower speeds to boost acceleration, some people feel that mild hybrid cars feel smoother and more powerful to drive. With the help of the battery, the engine doesn’t have to work as hard, so they can tend to feel less aggressive, even with the added power. Even in mild hybrid sports cars, their extra power boost can make acceleration feel smoother and safer.

A few final tips…

Here are a last few things to remember if you’re thinking about buying a mild hybrid car:

  • Mild hybrid cars might not be zero-emission, but most people see them as a pretty solid transition toward a hybrid car
  • Mild hybrid cars are basically just a normal petrol or diesel car with a battery for an extra boost
  • Most mild hybrid cars are going to have better fuel economy than a standard diesel or petrol car

Urban Jungle is not a financial advisor and information in this article should not be taken as advice or recommendation.