After more than a century of mass-producing internal-combustion-engine powered (ICE) vehicles, the world’s auto makers are rapidly switching their focus to electrification.

Some car makers have already set an end date for the manufacture of ICE vehicles, while others are forecasting significant growth in sales of electrified models across their range. 

Although the auto industry has been working on electric vehicles (EVs) for decades, the shift has seemingly come about rapidly for consumers, often leading to confusion about the different types of electrified vehicles available.

This guide aims to help you better understand the different types of electric cars, which fall broadly into four categories: hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), battery electric vehicles (BEVs) and fuel cell electric vehicles (FCEVs).

Mild hybrid 

Hybrid Electric Vehicles (HEVs) fall into two categories – so-called “mild” hybrids and the more common conventional hybrid, often also referred to simply as “hybrid”. Mild hybrids are the least electrified of all EV drivetrains but the technology has become increasingly popular in recent years as car makers strive to reduce the fuel consumption and emissions of ICE-powered vehicles.  

Like a regular hybrid, mild hybrids feature a combustion engine accompanied by an electric motor system that provides a modest amount of electric support to reduce fuel consumption. 

This electric support is typically deployed when the vehicle is accelerating from rest, which represents one of the highest demands on power and hence fuel consumption. 

Unlike in a regular hybrid, the electric motor in a mild hybrid does not power the vehicle independently of the ICE, but instead assists the combustion engine when required. 

Mild hybrid technology such as that used by the Mercedes-Benz C-Class pairs four-cylinder petrol or diesel engines with an integrated starter generator (ISG) and a 48-volt vehicle electrical system. The technology can also be used with other engine types, such as inline sixes and V8s. 

The ISG is essentially a starter motor and a generator built into a high-performance electric motor located between the engine and the transmission. 

This electric motor is connected to a 48-volt battery that supplies the vehicle electrical system and the ISG with electricity. 

In the C-Class engines, the mild hybrid system temporarily delivers an additional 15kW and 200Nm of electric power and torque when the vehicle starts and accelerates. 

The additional “shove” of electric power reduces the need for the ICE to use extra fuel to boost its performance. Some sources estimate the fuel savings of mild hybrids to between 10-15% of that of a comparably sized and powered conventional vehicle.  

Hybrid electric vehicles (HEVs) 

Think “hybrid” and it’s likely the first brand that springs to mind is Toyota and the first model is Prius. Since it was launched in 1997, the Toyota Prius has become the poster child for HEVs worldwide. 

Toyota has also gone on to apply HEV technology to an ever-growing list of its models, notching up more than 15 million hybrid sales in the past 24 years, including more than 200,000 in Australia. 

Because they retain an ICE, assisted by an additional battery and one or more electric motor/generators, HEVs are regarded as an easy transitional step towards a BEV for people who may be nervous about EV technology and electric range anxiety. 

A hybrid vehicle cannot be plugged in to recharge. 

The HEV’s battery is recharged by the ICE and an on-board electric motor generator as the vehicle coasts or decelerates in a process known as regenerative braking.

This helps reduce the fear people have about EVs and the possibility of being inconvenienced, or worse, by running out of battery charge.
 
The combustion engine and electric motor in an HEV shift the workload seamlessly between themselves, with the ICE doing most of the work but assisted by the electric motor when accelerating or under load. 

The vehicle will also operate on its battery alone, under low load conditions.  

The main advantage of an HEV over a conventional ICE-powered vehicle is significantly better fuel consumption and lower emissions, thanks to the electric motor playing a fuel-saving role in supporting the combustion engine during acceleration and the ICE not running at idle under certain conditions. 

Because an HEV has a larger battery pack than a mild hybrid, the electric motor can provide the ICE with more support more often, including at road speeds, which in turn equates to even better fuel consumption. 

Toyota estimates that its hybrids use about 30% less fuel than an ICE-powered equivalent. 

However, because the traction batteries used in HEVs are smaller than those used in PHEVs or full battery electric vehicles, the electric-only range of HEVs is limited.

Critics also point out that HEVs remain dependant on fossil fuels to operate. 

Plug-in hybrid electric vehicle (PHEV) 

If HEVs are the first step on the journey to electrification, PHEVs are the next, effectively bridging the gap between HEVs and BEVs. 

PHEVs retain the convenience and range of an ICE-powerplant but supplement this with the ability to offer an expanded range of electric-only motoring, courtesy of their larger drive battery and more powerful electric motors. 

Unlike an HEV which recharges its battery exclusively while driving, the larger PHEV battery can be recharged by plugging in to an electrical power source, just as you do a BEV. 

Also like a BEV, the PHEV can drive on electric power alone, albeit for a limited distance. 

The vehicle typically runs on electric power until the battery is nearly depleted and then the car automatically switches over to use the ICE.

The Mitsubishi Outlander PHEV, for instance, has an electric driving range up to 54km, which Mitsubishi claims is enough for the daily driving requirements of many Australian families. 

PHEVs like the Outlander can operate in three distinct driving modes: EV Drive with the front and rear electric motors using only energy stored in its battery; Series Hybrid with the ICE operating exclusively as a generator to recharge the battery on the go; and Parallel Hybrid, like the Toyota RAV4 Hybrid, in which the ICE drives the front wheels directly, assisted by the front electric motor, with the rear electric motor driving the rear axle. 

Because PHEVs can travel for a reasonable distance on electric-only power, their combined cycle fuel consumption is typically lower even than an HEV. 

In the case of the Outlander PHEV, this combination contributes to its impressive 1.7L/100km combined cycle fuel consumption figure. 

PHEV drivers who plug in and recharge regularly to drive short distances will rarely need to fill up with fuel, so can drive without generating tailpipe emissions.

Alternatively, a fully fuelled PHEV can travel longer distances than many BEVs and continue to operate regardless of the charge state of its lithium-ion battery, because the vehicle can also operate like an HEV and continue to run on the ICE. 

The main upside of a PHEV is the ability to travel commutable distances on electric power, in which scenario they don’t generate tailpipe emissions. 

They are also able to undertake longer journeys without the need to use battery charging infrastructure enroute. 

The downside is that PHEVs still feature a fossil fuel burning ICE engine and their electric-only range is limited.

Battery electric vehicle (BEV) 

The next step up from a PHEV is the battery electric vehicle (BEV), commonly known as an EV.

BEVs have no combustion engine and instead are powered exclusively by an electric motor (or motors) drawing charge from a high voltage battery pack, typically lithium-ion in modern EVs.

Because they can drive entirely without a fossil-fuel-burning engine, BEVs generate no tailpipe emissions.

However, BEVs need to get the power to charge their large batteries from somewhere, and the source of this power dictates whether they are truly emissions free (e.g., coal-fired or solar). 

Unlike ICE-powered vehicles, which tend to be least fuel efficient in stop-start urban driving, BEVs travel further in this situation thanks to their regenerative braking technology.

The more you slow down or stop, the more the battery is recharged. 

A large battery capacity is the key to an EV’s range and can be thought of as like a fuel tank.

The larger the battery, the further the vehicle will travel and, in combination with the electric motor (or motors) it powers, the more performance the BEV will have. 

Batteries are the single biggest cost component of a BEV, so the more range and/or performance your BEV has will directly affect its purchase price. 

The Nissan Leaf e+, for instance, is an extended-range version of the regular Leaf EV and features a 62kWh battery, 22kWh larger than the battery in the regular model. 

The bigger battery pushes range out to 385km, a handy extra 115km over the standard Leaf.

It also liberates an extra 50kW and 20Nm from the electric motor, shaving a second off the 0-100km/h time. 

At $60,490 (MRLP) the Leaf+ is about $10,500 more expensive than the regular model, which Nissan says is pretty much all accounted for by the extra battery capacity. 

When it comes to charging, most EVs offer multiple options, from the slowest AC charging to the fastest DC charging. 

The flat-to-full charge times for the Nissan Leaf e+ battery for instance varies from 32 hours on a household AC plug, to 11.5 hours on an AC Wallbox, to 1.5 hours on a standard DC fast charger. 

Hydrogen fuel cell electric vehicle (HFCEV) 

While BEVs are leading the race to be the dominant alternative to internal combustion engines, hydrogen fuel cell electric vehicles (HFCEVs) are regarded by some experts as the ultimate solution to the problem of tailpipe CO2 emissions. 

This is because hydrogen is an already abundant element, it can be made cleanly and safely from renewable energy sources using nothing more than water and green electricity, and HFCEVs emit nothing but heat and water. 

Like BEVs, HFCEVs are powered by an electric motor (or motors), but where BEVs use lithium-ion batteries recharged by plugging into the electricity grid, an FCEV carries its energy source as hydrogen in high-pressure tanks beneath the vehicle. 

The hydrogen is converted via a special on-board catalyst called a fuel cell, which combines hydrogen and oxygen to generate an electric current, which in turn powers the vehicle’s electric motor.

The only by product of this process is distilled water, which is discharged as vapour from beneath the vehicle, sometimes seen as a visible splash when an HFCEV driver presses hard on the accelerator.

HFCEVs are also equipped with other advanced technologies to increase efficiency, such as regenerative braking systems, which capture the energy lost during braking and store it in a battery.

Just like petrol, diesel, or LPG, the hydrogen in an HFCEV’s tank must be replenished when it runs out and therein lies one of the major barriers to the take up of HFCEVs, because hydrogen refuelling stations are rare and expensive to build. 

This lack of infrastructure has proven a challenge worldwide, despite HFCEVs offering some major advantages over BEVs, including greater range and much quicker refuelling times.

The Hyundai Nexo HFCEV, for instance, boasts a range of 666km and re-fuelling time like an ICE-powered vehicle of three to five minutes. 

Other benefits of HFCEVs include the fact they are more efficient and reliable than ICE-powered vehicles due to having fewer moving parts (a trait shared with BEVs), and they are significantly lighter than BEVs because they don’t need to carry heavy battery packs.  

Production HFCEVs have been on sale in international markets for several years now and the arrival in Australia earlier this year of two separate fleets of Hyundai Nexo and Toyota Mirai HFCEVs was seen as a significant step towards embracing the technology here, but they are currently not available commercially. 

But despite the optimism around hydrogen as the “fuel of the future”, it’s unlikely HFCEVs will overtake BEVs any time soon, due to the lack of vehicle choices, high costs, and lack of specialised refuelling infrastructure.