What are the disadvantages of a mild hybrid car?

    If you’re thinking about selling your car and buying a mild hybrid vehicle (MHEV), let’s weigh up the advantages and disadvantages. The two main advantages are that they have a better fuel economy and lower CO2 emissions than vehicles with a traditional petrol and diesel internal combustion engine (ICE).

    However, these are some of the disadvantages:

    1. The fuel savings are minimal compared to full hybrids or electric vehicles.

      2. They rely heavily on traditional combustion engines, providing limited environmental benefits.

      3. Their initial cost is higher than that of conventional ICE cars.

      4. They often deliver lower performance improvements, making them less appealing for those seeking substantial gains in fuel economy and emissions reduction.

      Read on as we examine mild hybrid cars in more detail and consider whether they are worth it.

      What is a mild hybrid vehicle (MHEV)?

      Mild hybrid cars are cheaper than full hybrid vehicles. But other cost factors add up.

      Defining the mild hybrid system

      A mild hybrid system combines a small electric motor with a traditional internal combustion engine to improve fuel efficiency and lower emissions. Unlike full hybrids, mild hybrids cannot power vehicles using electricity alone. Instead, the electric motor assists the engine during acceleration and can capture energy during braking.

      MHEVs enhance fuel efficiency and reduce environmental impact, making them an appealing choice for those looking for gradual benefits without transitioning fully to electrification.

      Key components and operation

      A mild hybrid system comprises the following: 

      • ⚡ Small electric motor
      • 🔋 48-volt battery
      • ⚡ DC/DC converter
      • ⚙️ Internal combustion engine

      When in operation, the electric motor assists the engine during acceleration, reducing fuel consumption and emissions. 

      The battery stores energy recovered during braking, which the motor can use later. The DC/DC converter manages power flow between the battery and the vehicle’s electrical systems, ensuring seamless integration and optimal performance.

      Disadvantages of mild hybrid cars

      Limited electrification benefits

      A mild hybrid doesn’t offer the full benefits of a full hybrid electric vehicle (HEV) or an electric vehicle (EV). Unlike HEVs and EVs, mild hybrids can’t solely run on electric power. This means that they offer smaller reductions in fuel consumption and emissions. 

      With mild hybrids, the electric motor primarily assists the internal combustion engine, so they are not as environmentally friendly as HEVs or EVs.

      Cost implications vs traditional vehicles

      Mild hybrid vehicles typically cost more upfront than traditional petrol or diesel ICE cars. Integrating an electric motor and other parts, such as a 48-volt battery system, increases manufacturing expenses. These added costs are often passed on to consumers, making mild hybrids more expensive. 

      Another factor to consider is that the fuel savings over time may not be substantial enough to offset the higher initial investment. This potentially means buyers will have to wait longer before seeing a return on their investment.

      Battery life and replacement costs

      Mild hybrids cannot move solely by their electric engines.

      The 48-volt battery in an MHEV has a limited lifespan and will eventually need replacing. While these batteries are generally less expensive than those in full hybrids or electric vehicles, they still represent a significant cost. 

      When they need to be replaced depends on usage and driving conditions. But owners should be prepared for this extra expense.

      Impact on vehicle weight and fuel consumption

      The addition of a mild hybrid system increases the vehicle’s overall weight, which can offset some of the fuel efficiency gains provided by the electric motor assistance. Although mild hybrids are intended to improve fuel economy, the added weight of the components may result in less significant savings than expected.

      Lack of government incentives and reduced savings

      Mild hybrid vehicles often do not qualify for the same government incentives as full hybrids or electric cars. Their financial appeal is significantly reduced without access to these subsidies, tax rebates, or grants. 

      This lack of incentives can make it harder to justify the higher upfront cost, especially when the fuel savings are modest.

      Financial considerations: purchase price, tax, and running costs

      Initial purchase price compared with other vehicle types

      Mild hybrids, in general, initially cost more to buy than traditional petrol or diesel vehicles. This is due to the added cost of the:

      • ⚡Electric motor
      • ⚡48-volt battery

      However, they usually cost less than full hybrids and electric vehicles, which come with more advanced technology and a higher price tag.

      Tax benefits for MHEV owners in the UK

      Because of their reduced emissions, mild hybrid vehicles may benefit from lower road tax rates than traditional petrol or diesel cars in the UK. However, they typically don’t receive the same level of tax incentives or rebates as HEVs or EVs.

      Long-term running costs and potential savings

      Over time, mild hybrids can provide slight fuel cost savings compared to conventional vehicles. The fuel efficiency improvements from the electric motor and regenerative braking contribute to these savings. 

      However, the decrease in running costs may not be significant, and quick, enough to compensate for the higher initial purchase price.

      Environmental considerations

      Carbon footprint comparison with conventional, fully hybrid, and electric vehicles

      Due to reduced fuel consumption and lower emissions, mild hybrids have a smaller carbon footprint than conventional petrol or diesel vehicles. But, as mentioned, their environmental benefits are less significant than those of full hybrids or electric cars. 

      Full hybrids offer greater reductions in carbon emissions by using electric power more extensively, while electric vehicles produce zero tailpipe emissions, providing the lowest carbon footprint.

      Renewable energy integration challenges

      Compared to fully electric vehicles, mild hybrids face challenges integrating renewable energy. While they do benefit from some regenerative braking, they still rely on traditional combustion engines for power. 

      This reliance limits the potential for directly using renewable energy sources. In contrast, fully electric vehicles can be charged using renewable energy, significantly reducing their carbon footprint.

      FAQs

      How long do mild hybrid batteries last?

      Mild hybrid batteries typically last 8 to 10 years, or 80,000 to 100,000 miles. Battery lifespan can vary based on driving conditions and maintenance, with some batteries potentially lasting longer with proper care.

      Are mild hybrid cars more expensive to insure?

      Yes, mild hybrid cars can be more expensive to insure compared to traditional vehicles. This is due to their higher repair costs and the added complexity of their systems, which can increase insurance premiums.

      How much does it cost to replace a mild hybrid battery?

      Replacing a mild hybrid battery typically costs between £300 and £600. Prices can vary depending on the vehicle’s make and model, the battery’s specifications, and warranty terms.

      Is it time to sell your car?

      Ready to learn more about valuing, maintaining, and selling your car? Check out more of our guides here, covering everything from hybrid and electric car depreciation to converting your car to dual-LPG fuel.