Different Types of Electric Cars
4th February saw the Government announce that it intends to phase out the sale of all new petrol and diesel cars by 2035, bringing the previously announced date forward by five years. It has also included hybrid vehicles in the commitment for the first time.
However, hybrid technology is playing an increasingly important role in the current market, as drivers use these vehicles as a stepping-stone to full electrification. In fact, there are now so many cars on the market featuring some form of electrification that it’s easy to get confused by the claims and terminology. In this post we look at the key types of electrification on offer and describe how they differ.
Electric v Hybrid
The first distinction to make is between pure electric cars and hybrids. Pure electric cars are sometimes called Battery Electric Vehicles or BEVs, they have a large bank of batteries and one or more electric motor. Their batteries are topped up by plugging the car into a charger at home or at the workplace; or at one of thousands of public charge points. They also recover energy through ‘regenerative braking’ which turns the engine into a generator when the vehicle is slowing.
All hybrid cars have more than one power source; batteries and electric motors plus either a petrol or diesel internal combustion engine (ICE). There are quite a few different types of hybrid which we’ll look at in more detail below.
Series v Parallel Hybrids
This point is a little moot at the moment since the only mainstream series hybrid, The BMW i3 range extender, has been withdrawn from sale in Europe. Series hybrids only use electric motors to power their wheels, with the energy coming from their battery packs. Their internal combustion engines work purely are generators to top up the batteries if they are running low on charge. One of the key advantages of series systems is that it allows the ICE to run at a constant speed, which maximises its efficiency.
With most parallel hybrid systems, both the electric motors and ICE can power the driven wheels. They use sophisticated electronics to assess the driving conditions and the state of charge of the batteries, and use a combination of the electric motors and the ICE in the most efficient way possible. Many parallel systems will also allow the driver to override the electronics and choose to run on battery power alone for a certain distance.
Full v Mild Hybrids
With a full hybrid, the car can usually be driven by battery power alone for a short distance. This will vary from model to model and on whether the vehicle is a plug-in hybrid or not – see the section on this below. For non-plug-in hybrids, the distance that they can travel using just electrical power is usually very limited, as they tend to have small battery packs. In non-plug-in hybrids the electric motor is really there to assist the ICE in powering the car, making it more efficient by reducing the effort the ICE puts in and cutting its fuel use and emissions.
Full hybrid cars also use their electric motors to boost acceleration and this is capability is used to a greater extent in cars like BMW’s i8 or Porsche’s Cayenne E-Hybrid that have more of a focus on performance. Perhaps the most appealing thing to drivers about full hybrids is that they can continue to be driven even if their batteries are completely discharged, by using their ICEs.
Mild hybrid registrations have been growing very rapidly as manufacturers seek to make their petrol and diesel powered vehicles more fuel-efficient. In 2019 they accounted for 4.3% of all car registrations, not far behind the 6.3% accounted for by full hybrids and ahead of the 3.3% for pure electric vehicles*.
Mild hybrids work in a similar way to a full hybrid, but their batteries and electric motors are not large enough to power the vehicle on their own. They work in conjunction with the ICE to enhance efficiency and to assist in the stop-start function by spooling the engine up to the right speed before ignition. However, some systems don’t actually play any part in driving the vehicle and instead just recover some kinetic energy when braking and use this to power ancillary electrical systems.
Plug-in v Non-Plug-In Hybrids
Non-plug-in hybrids come in both full and mild variants as discussed above. Some manufacturers refer to them as, ‘self-charging hybrids’ in a bid to differentiate them form those that you have to plug-in. While this description is strictly correct, plug-in hybrids (PHEVs) can also self-charge to a certain extend and offer other advantages.
Plug-in-hybrids move electrification a step closer to that of pure electric vehicles. They have much larger battery packs that, as the name suggests, can be charged using a cable as well as being charged up by the ICE and regenerative braking as they are driven.
The main advantage of PHEVs is that they have the ability to drive for longer distances on battery power alone. This means that if you have a relatively short daily commute you should be able to travel using just the electric motor, after charging the batteries overnight, drastically reducing running costs. If your employer provides workplace charging, a longer purely electric commute becomes possible.
PHEVs only work at their best if they are charged via a cable, unlike non-plug-ins that are designed to operate at maximum efficiency using a combination of their powerplants. In fact, if they’re not plugged in to charge regularly, they can be less efficient than regular petrol or diesel cars as they have to carry the weight of their electric motors and battery packs.
What about Hydrogen?
There are only a handful of hydrogen fuel-cell powered cars (FCEV) available in the UK and the infrastructure for refuelling them is still extremely limited. However, interest in hydrogen is growing, mainly because refuelling them is very similar to refuelling an ICE car, taking just a few minutes. They, like BEVs, run with zero harmful emissions at the exhaust pipe, as the hydrogen fuel cell technology only produces water as a result of its energy generation.
In fact, all FCEVs are also BEVs as they have to carry a battery array to provide instant power when the vehicle pulls away; fuel cells take a while to get into the stride of providing electrical energy and this isn’t viable for stop-start driving.
Which make a good company car choice?
From April 2020, BEVs will attract a company car benefit-in-kind tax rate of 0%; this is likely to have a significant impact on their popularity among fleet drivers. Plug-in hybrids will also see substantial reductions in tax rates depending on their CO2 emissions and the distance they can travel using battery power alone. Even highly efficient non-plug-in hybrids fair well compared to other vehicles, simply because their CO2 emissions tend to be lower than regular petrol and diesel models.
To see how company car tax varies by emission levels and electric-only range, take a look at the full tax tables to 2023.
If you’d like to know more about electrification, and how alternative fuel vehicles could work for your fleet, visit our hub.
*SMMT – Electric Vehicle and Alternatively Fuelled Vehicle Registrations December 2019