Hybrid cars: what changes between mild hybrid, full hybrid, plug-in hybrid

Until a few years ago, it was easy to understand the type of motorisation of one's car. The main division was between petrol and diesel, to which methane and LPG could be added. With the arrival of hybrid cars, the variables and confusion among users have increased. Because while the wording on the registration certificate is sufficient, there is a profound difference between a 12-volt mild hybrid, full hybrid or plug-in hybrid car. Let's find out the differences.

Mhev (Mild Hybrid Electric Vehicle) systems, often christened 'light hybrids', are the first step in electrification. Versions with Mild Hybrid technology have a parallel electric system, powered by 12 or 48 volt batteries working together with a small electric motor. Capable of recovering energy during braking, the 12-volt Mhev system is not able to move the tyres independently but provides energy during vehicle restart, thus reducing consumption and polluting emissions. Despite the characteristics of the system, where there is practically no electric traction, Mhev cars are in most cases homologated as hybrids, thus benefiting from all the advantages, starting with access to restricted traffic zones and road tax exemptions in certain regions. It is a different story for the 48-volt mild hybrids, which are now capable of moving the car in full electric mode for several kilometres.

The second step of electrification sees the presence of Hev (Hybrid Electric Vehicle) models, increasingly christened as full hybrids, where the electric motor works together with the Ice (Internal Combustion Engine) and is able to travel 100 per cent in electric mode for more kilometres than 48-volt mild hybrids. The electric motor contributes more to lower fuel consumption and emissions than Mhev systems, but it takes up more space and involves higher costs and weight. The batteries are recharged during braking and thanks to the presence of the heat engine, while there is no power outlet that can connect to charging stations.

For 'plug-in' models, one has to switch to the Phev (Plug-In Hybrid Electric Vehicle) where there is a combustion engine and the electric motor is also recharged from the wall socket. The zero-emission range can be up to 100 kilometres and petrol consumption is significantly reduced when travelling with a charged battery. Completely opposite situation when the battery is empty, where plug-in cars become anything but economical and environmentally friendly.

The acronym Erev (Extended-Range Electric Vehicles) identifies vehicles where the internal combustion engine is only used as a power generator to recharge the traction battery when the charge level is low. Erev's recent additions include the Nissan Qashqai e-Power, where there is no power plug but the petrol-powered internal combustion engine is only used to generate the energy needed to charge the electric motor battery and not to move the wheels.