If you’re thinking about making the switch from a petrol or diesel car to something with electric power, well ahead of the 2030 cut-off date for banning the sale of brand-new petrol- or diesel-only vehicles, then you might find the automotive world a confusing whirl of terminology right now. For instance, what’s an ICE? How does an MHEV differ from a PHEV or a HEV? And is an electric car a hybrid? Well, thankfully, we’re here to help you through the confusion...
What Are The Main Types Of Cars?: Internal Combustion, Hybrid And Electric
Before we drill down into various weird acronyms and initialisms in greater detail, it’s worth clarifying exactly what the 3 main categorisations of cars are. So, without further ado, they are internal combustion engine (known as ICE) vehicles, hybrid vehicles (known as MHEV, HEV, PHEV, FCEV and REx EV – we’ll explain these more fully in a sec), and then electric cars (EV). And here’s a rundown of each of these vehicle types:
Internal Combustion Engine (ICE)
This is what you might term a ‘traditional’ car. It has either a pure petrol or pure diesel powertrain onboard, which burns its preferred type of fuel in a process known as internal combustion – hence, internal combustion engine and then the acronym ICE… which also used to mean ‘in-car entertainment’ once upon a time, but we digress.
It is the sale of brand-new ICE cars which will be outlawed by the UK Government’s proposed ban, that’s due to take effect in 2030. From that date on, you will not be able to buy any vehicle from a dealership which ONLY has a petrol or diesel engine onboard. However, it does not mean that petrol and diesel cars will be immediately outlawed entirely – the sale of used ICE vehicles will continue, fossil-fuel stations will remain open well into the 2030s and maybe beyond, and the existing ICE fleet of the entire UK will (as far as we are aware) still be allowed to drive about on the country’s network of roads. Admittedly, there’s probably going to come a point in the much-more-distant future when the personal use of ICE vehicles might well be outlawed on public roads entirely, but that’s not been confirmed yet and it will probably be decades away from now if it even does happen at all.
In terms of electrification of their drivetrains (i.e., the bits of the car concerned with propelling the vehicle forward down the road, specifically the engine and gearbox), there is none to speak of whatsoever with an ICE car. The only electrical systems onboard ICE vehicles are the old and familiar ones – the lights, the radio/sound system, the wipers and the heating/ventilation, and so on. These are powered from a traditional 12-volt battery, which is kept charged by the car’s alternator when the vehicle’s engine is on, and that’s pretty much that for petrol and diesel.
Hybrids (MHEVs, HEVs, PHEVs, FCEVs And Range-Extended (REx) EVs)
The most widespread and possibly confusing category, but it is quite simple if you just focus on the word ‘hybrid’. That, going by its most basic definition, means the vehicle has 2 forms of propulsion onboard – typically an internal combustion engine and an electric motor.
However, even that definition becomes a little hazy with the first type of hybrid, the mild-hybrid electric vehicle. The MHEV uses either a 12- or a 48-volt electrical system that involves a very small battery pack, typically less than 1kWh, and usually a device called a belt or integrated starter-generator (BSG or ISG) that acts in place of a traditional starter motor. This B/ISG can also serve as an additional ‘power booster’ for the petrol or diesel engine it is attached to, during periods of acceleration, to assist with the propulsion of the car. They can also harvest otherwise lost kinetic energy when decelerating or braking, and some MHEVs will even allow the vehicle to coast ‘engine off’ as it slows down. The key thing to remember, though, is that MHEVs cannot drive on electric power alone – the hybrid technology here merely saves some fuel and reduces the CO2 emissions by a marginal amount accordingly.
If you want electric-only running from your hybrid, then you need to step up to a hybrid electric vehicle (HEV). The most famous example of this technology is the Toyota Prius, and indeed Toyota and associated company Lexus is probably the market leader in this technology. A HEV has a larger battery pack than an MHEV, usually in excess of 1kWh but no more than 5kWh, and also an electric motor that IS capable of driving the car forward on its own for short periods of time – typically a mile or two at most, usually in city traffic conditions. HEVs are sometimes referred to as ‘series’ or ‘parellel’ hybrids, because both the ICE and the electric motor can drive the car’s wheels (either on their own or in tandem), and then also as ‘self-charging’ hybrids, because they – like MHEVs – do not have any facility to be plugged into the mains to replenish the onboard battery pack. Instead, the vehicle’s ICE and its brakes recharge the propulsion system’s battery while the car is on the move, hence the ‘self-charging’ bit of the name. However, some people find this last phrase somewhat contentious, so it’s best to simply call these vehicles HEVs.
The step up from a HEV is the plug-in hybrid electric vehicle, or PHEV. This is the ‘halfway-house’ technology for those looking to adopt electric power, because on paper a PHEV offers the best of both ICE and EV worlds. PHEVs usually have much larger battery packs than HEVs, normally more than 10kWh and rarely bigger than 30kWh, which means these vehicles can drive on electric power at higher speeds (some up to 87mph) and for longer distances. The usual electric range of a PHEV nowadays is around 30 miles, but there are some which are pushing 40, 50 and even 60 miles; the super-rare Polestar 1 PHEV, however, was said to do up to 78 miles on electric power alone. Yet PHEVs also have a sizeable petrol engine onboard, or – in the rare case of a few Mercedes models, like the E 300 de and GLC 300 de – a turbodiesel motor, which means they can keep on driving on good old fossil fuels once their electric reserves are depleted; again, like HEVs, the normal status quo here is that both the ICE and the electric motors can drive the wheels of the vehicle directly. PHEVs claim outlandishly high official WLTP mpg figures (usually in the range of 100-300mpg) and markedly low CO2 outputs (in the main, less than 60g/km), which makes them appealing for taxation purposes, but caution must be sounded here – to ever attain a 100mpg+ economy figure from a PHEV in real-world use, you need to drive it mainly on electric every day and charge it overnight. The more you use a PHEV’s ICE, the more likely you are to see more like 40-50mpg or thereabouts.
After this level, there are only 2 more types of hybrids to talk about, although one of them – the fuel-cell electric vehicle (FCEV) – isn’t particularly common… yet. This replaces the onboard ICE with a hydrogen fuel-cell, pairing it to the electric motors and batteries, and in theory an FCEV is the silver bullet in the mid-term: it offers rapid refuelling rates, like an ICE vehicle, and all the long-range driving duties of a PHEV, comfortably outstripping an electric vehicle in this department, yet the fuel cell emits nothing more than water vapour from its tailpipes so it’s a zero-emissions machine too. There are just 2 FCEVs on sale in the UK today, which are the Toyota Mirai and the Hyundai Nexo, and the issue with running hydrogen cars here at the moment is that the hydrogen-refuelling infrastructure in this country is currently in its infancy; the plan was to have 65 hydrogen filling stations in the UK by 2020, but in reality there are fewer than 15 that are operational as at the time of writing.
The final hybrid type is the range-extended electric vehicle (REx EV). The 2 most notable examples of this unusual technology that have been on sale so far are the Vauxhall Ampera (2012-2015) and the BMW i3 REx, which was still on sale very late into the i3’s life. In this set-up, the main propulsion is always the electric motor – unlike in PHEVs, the onboard ICE cannot drive the wheels of the car directly. Instead, the fossil-fuel-burning engine will be used as a generator to put charge back into the EV’s larger battery pack while it is on the move, extending its driving range (hence the name) as the car goes. The ICE in these vehicles is normally very small and underpowered – in the i3 REx, for instance, it was a 647cc 2-cylinder petrol engine from a motorbike, developing just 37hp – and of course because fuel is being burnt, there are some (nigh-on negligible) tailpipe emissions. However, just like ‘full’ EVs, these REx models can be plugged into the mains to charge their battery packs instead. It looked like range extenders were going to be an evolutionary dead-end, but reputedly Mazda is working on a REx version of its MX-30 EV, using a small rotary petrol engine to do the range-extending work – so the REx EVs could be making a wider comeback in the years ahead.
Electric Cars (EVs)
As their name suggests, pure EVs do not have any form of internal combustion engine (ICE) onboard at all. Not even a small petrol engine designed for range-extending duties (see above in Hybrids). For this reason, they do not have any exhaust pipes (even the EV range extender must have an exhaust and minimal emissions to go with it, if it’s burning any fuel at all) and so this is why EVs are often called ‘zero-emission vehicles’ – because they put out 0g/km of CO2 or NOx or anything else when they’re driving along.
It is EVs which our Government, and the governments of many other countries, wish for us to migrate to in the mid-term, so there has been a boom in the number of pure EVs in recent years – car-buyers have far more choice in this automotive arena as a result. The only way to replenish an EV’s battery pack to any serious degree is to plug it into the mains electric, either on slower AC connections or faster (rapid or ultra-rapid) DC public chargers. The most famous EV company is, naturally, Tesla, but many of the legacy carmakers are announcing they will be shifting to only selling EVs in the coming years – examples being MINI and Jaguar, the former in 2030 and the latter even earlier, by 2025.
What Are The Drawbacks And Benefits Of Hybrids Versus Electrics?
Leaving ICE cars out of it from now on, the benefits of hybrids are that they are more usable for more of the time than electrics – certainly, if we’re talking about the state of EV battery technology and driving range prevalent in 2022. Both MHEVs and HEVs drive exactly like ICE cars – you merely put petrol or diesel in them, as and when the fuel tank gets low, and then you drive them around normally. The onboard systems determine when the car will use its MHEV tech to save a bit of fuel, or alternatively drive in electric-only mode if the battery has enough juice (HEV). To this end, they are just as good in city driving as they are doing long-distance motorway journeys, and if you don’t like the idea of faffing around with charging cables and electrical sockets, these are the hybrids for you.
PHEVs are a little more complicated. Ostensibly, they’re designed to do everything – zero-emission city driving for the vast majority of the time, then long-haul treks when you need them to. In reality, the larger battery packs required for a PHEV and their stronger electric motors add a lot of weight to the vehicle, usually about 200-300kg. This means that, once the battery pack is exhausted after 30 miles or so of electrically assisted driving, the onboard ICE has to lug around the vehicle’s body, PLUS all the hybrid magubbins which is now ‘dead’ until it is recharged with a mains plug-in cycle. So fuel economy takes a big hit if you go on a motorway in a PHEV and, even worse, if you do what many owners do – use the car’s control systems to get the onboard ICE to charge the battery pack while you’re on the move – then the fuel consumption becomes about as bad as driving around in a big V8 petrol. What you’re asking the PHEV’s engine to do here is not only drive the car, but also send a huge electrical current to the battery pack to replenish its reserves. PHEVs, therefore, are absolutely ideal for semi-urban commuters – those who drive no more than 30 miles to work and back each day, who can regularly plug the car in either at home or their office, and then only use the ICE for the occasional longer weekend jaunt to see relatives or so on. If you just regularly do lots of long-distance motorway work, a PHEV is not the answer for you at the moment.
The benefit of EVs is that current legislation favours these hugely in terms of taxation, and also – if you charge mostly at home – the cost of domestic electricity is far cheaper per-mile than fuel is for an ICE vehicle. That said, if you use rapid or ultra-rapid chargers, the price of each unit of electricity (kWh) rises significantly, meaning it isn’t always great value to recharge the EV quickly. Also, the manufacturers do caution against repeated rapid/ultra-rapid charging for the sake of the battery’s long-term health, so some home charging is not only inevitable, it is highly recommended. EVs, of course, give you the clearest conscience as a motorist: while there is of course a carbon footprint involved in manufacturing the vehicle (and its lithium-ion batteries) in the first place, and there is also a carbon consideration further down the line when charging (due to the fact the UK’s national electricity grid is not 100% powered by renewable energy sources at this time), the fact of the matter is that when they’re in motion, EVs emit nothing harmful into the atmosphere of our planet whatsoever.
What Are Plug-In Vehicles, Then?
This only refers to PHEVs, REx EVs and pure EVs, and the clue is in the name – these vehicles all have some capacity to be plugged into the mains, to recharge the electric portion of their drivetrains. This will usually take the form of a ‘flap’ on the body, which looks a lot like the traditional fuel-filler flap of an ICE vehicle. Behind this flap will be a charging port, almost universally a Type 2 connection of some sort (standard Type 2 or CCS Combo 2, for cars with rapid charging capabilities), although there are a handful of EVs (e.g., Nissan Leaf) which use the CHAdeMO socket instead. For home-charging purposes, PHEV, REx EV and EV owners can either use the Type 2 Mode 2 cable (has a Type 2 socket one end, a control box in the middle of the cable and a 3-pin domestic plug the other end) for the slowest AC charging, or the Type 2 Mode 3 cable (Type 2 sockets both ends, no control box) if they have an untethered wallbox – this means the wallbox itself does not have an extendable cable. The Type 2 Mode 3 cable is also used for public charging on AC connections which are also untethered, but for all DC public charging points (rapid and ultra-rapid speeds), the units are tethered – this means the heavy-duty extendable reel cable with the requisite CCS Combo 2 connection is attached to the charger itself, rather like a pump handle and hose is attached to a petrol pump. Quick note: there are only a handful of PHEVs which can DC rapid-charge – they mostly only have an AC Type 2 connection to work with, therefore.
And Electrified Vehicles?
This is a catch-all term which relates to any vehicle that is a hybrid or an EV – as in, it has some form of electrical propulsion and/or fuel-saving system fitted to it. So in essence, it is any vehicle which isn’t a pure ICE model. It’s not often used, mainly appearing in motoring journalism reviews of modern-day cars more than anything.
So, to recap:
ICE = a pure internal combustion engine vehicle, either petrol or diesel, with no electrical systems onboard save for the 12-volt circuit for lights, wipers, radio/stereo etc.
Hybrid = any vehicle with 2 forms of motive power onboard (usually petrol and electric, but sometimes diesel and electric, and even in rare cases hydrogen fuel-cell and electric), or a vehicle with an electrical system designed to capture otherwise-lost kinetic energy for the purposes of saving fuel/reducing emissions (mild hybrid electric vehicle, or MHEV), or a range-extended electric vehicle (e.g., BMW i3 REx).
Electric Vehicle (EV) = ONLY has an electric propulsion system onboard; there is no internal combustion engine of any sort fitted to the vehicle.
Plug-In Vehicle = refers only to plug-in hybrids (PHEVs), range-extended electric vehicles (REx EVs) and pure electric vehicles (EVs). Denotes the ability for the vehicle to be plugged into mains electric, either at home or at public charging points, in order to recharge the onboard electric-propulsion part of its drivetrain.
Electrified Vehicle = any vehicle that ISN’T a pure ICE – so MHEVs, HEVs, PHEVs, FCEVs, REx EVs and EVs.