THE term “electric car” is usually applied to a battery electric vehicle (BEV) but these pure electric cars – generally known as EVs – are part of a broader advance towards electrification that embraces several types of hybrids and hydrogen fuel-cell cars as well. Here we explain the different variations.
Micro-hybrid/mild hybrid (MHEV)
An element of electrification will increasingly be featured in a large numbers of mainstream cars (vans, too, such as the all-new 2.0-tonne Ford Transit), which are sometimes referred to as micro-hybrids or mild hybrids, although there is no firm definition of these terms. These are often referred to as MHEV (Mild Hybrid Electric Vehicle).
Sometimes the term micro-hybrid is applied to any car with automatic stop-start, with some models’ stop-start systems also incorporating an element of regenerative braking.
The term mild hybrid can also used to describe certain types of hybrid set-ups where electric drive is used to assist a car’s petrol engine but the car is never propelled by the electric motor alone. Honda’s earlier IMA (Integrated Motor Assist) hybrid models fell into this category.
Audi has equipped all of the models in its latest A7 range with what it calls a mild hybrid system, which includes such features as a 48-volt primary electrical system, a belt alternator starter (BAS) combined with a lithium-ion battery and recuperative braking system. Between 34 and 99mph, the A7 can coast with the engine switched off and then restart automatically when required via the BAS.
Far more cars are likely to become mild hybrids as the industry increasingly adopts these 48-volt electrical systems, which are in part a response to the increasing demands being placed on cars’ electrics by the fitment of more and more electrical equipment such as heated seats.
The adoption of 48-volt systems also opens up all sorts of under-the-bonnet applications as well, including electric superchargers – sometimes called e-chargers – and, as in the case of the Audi A7, mild hybrid systems.
Bentley and Mercedes are among the other manufacturers to have introduced cars with 48-volt set-ups.
A hybrid vehicle is usually defined as one that combines two forms of propulsion. Most “full hybrids” have a petrol engine and an electric motor, although there are diesel-based hybrids as well.
Hybrid drivetrains were pioneered by Toyota and its luxury brand, Lexus, with the first Toyota Prius appearing in 1997. Most of the main manufacturers now include hybrid models in their line-ups. The first diesel hybrid, launched in 2012, was the Peugeot 3008 HYbrid4.
Hybrid systems vary enormously in terms of their detailed design, and in particular in how the power from the internal combustion engine and from the electric motor is combined.
Not all hybrids are capable of “electric-only” operation and those that are will typically only run on electric power alone when driven gently for short distances.
A plug-in hybrid. or PHEV (plug-in hybrid electric vehicle) is more “electric” than a standard hybrid. Usually it will have a much bigger battery, which can be topped up from the mains, and a more powerful electric motor. A PHEV is usually capable of running in electric-only mode for several miles. Some cars – for example, the Toyota Prius and the Hyundai Ioniq – are available in both standard and plug-in hybrid versions.
The specifications of the standard hybrid and plug-in hybrid variants of the Ioniq highlight the differences between the two types. The standard hybrid has a 32 kW electric motor, while the plug-in has a more powerful 45 kW unit. The battery in the plug-in is much larger too – 8.9 kWh compared with just 1.56 kWh, for a claimed electric-only range of 39 miles.
PHEVs vary as much in the detail of the powertrains as standard hybrids. and the distinction between a PHEV and an electric car with a range extender engine (for example some versions of BMW’s i3) is quite distinct.
While the primary source of propulsion on a PHEV is the internal combustion engine, the drive assisted or for a short distance replaced by electric motor – usually built into the drivetrain – on an electric car with range extender the propulsion is only by the electric motor(s) while a usually small internal combustion engine drives a generator to recharge the batteries.
The 192mph new Porsche Panamera Turbo S E-Hybrid Sport Turismo combines a 550bhp 4.0-litre twin-turbocharged V8 engine and a 136bhp electric motor in the drivetrain to develop a total of 680bhp – with an electric-only range of 31 miles.
By comparison the new MINI plug-in hybrid can switch between an internal combustion engine driving just the front wheels and an electric motor driving the rear wheels only – or combine both systems for extra performance. It starts in electric mode before switching to the engine will can also recharge the battery.
While PHEVs may be eclipsed in the long run by pure electric cars that are able to match today’s petrols and diesels for range, they represent an important bridging technology that will be one of the main drivers of electrification over the next few years.
PHEVs currently out-sell pure electric cars by a large margin, and for the foreseeable future, far more motorists will get their first taste of electrification in a PHEV than in a pure electric car.
Pure electric (BEV)
A pure electric car, generally known as an EV (electric vehicle) – or a BEV (Battery Electric Vehicle) has an electric motor and a large traction battery. Electric cars are recharged from the mains, either from the domestic electricity supply or from dedicated public charging points which charge at varying speeds.
Electric vehicles have been a small but ever present-element in the motor industry from the very beginning but the current age of electric motoring began less than a decade ago with the introduction of models such as the Mitsubishi i-MiEV, the Nissan Leaf and the Renault Fluence ZE.
At the same time, the opportunity presented by electrification has also attracted powerful new entrants to the market, most notably Tesla. Founded in 2003. Tesla launched large scale all-electric car production with the Model S in 2012, followed by the Model X SUV in 2015 with the more affordable Model 3 just coming on line.
A key selling point has been its own network of charging stations across Europe, which were initially free to use for Tesla drivers, with superchargers able to give enough charge for 200 miles in the time it takes for a coffee break.
Tesla rarely reveals details of production numbers but is the global leader of plug-in electric vehicles also a key developer in the necessary battery technology, its production of the premium cars reportedly exceeding 250,000.
Renewed interest in electric vehicles has been driven by growing concern about the environmental impact of motoring, and by improvements in key technologies such as lithium-ion batteries.
Most of the main car-makers now have ambitious electrification plans – including those at the heart of the business car market such as the German premium manufacturers with BMW promising PHEV and full battery electric cars across its brands – BMW, Rolls-Royce and MINI – and model ranges for the next generations.
Hydrogen fuel cell
The current hydrogen-powered cars, which use hydrogen fuel cells, are best seen as a sub-category of electric cars. The main examples are the Toyota Mirai and the Honda Clarity Fuel Cell, which is only sold in Japan and the US.
Like an electric car, a hydrogen fuel cell car has a battery and an electric motor but with a hydrogen fuel cell stack generating the electricity – with water the only emission – rather than a charge from the mains. This means these cars offer more range than the first crop of pure battery cars, but that advantage is rapidly being eroded as the range of pure electric vehicles improves.
At over over £53,000 for the Hyundai ix35 Fuel Cell and over £60,000 for the Toyota Mirai – the only hydrogen fuel cell cars on sale in the UK – they are much more expensive than most battery electric models, but less than the current Teslas, Model S and X.
From a driving point of view, a hydrogen fuel cell car behaves in much the same way as any other electric car. Although range is less of an issue – both ix35 and Mirai are capable of around 300 miles.
In the past, BMW offered a limited run of hydrogen-powered cars capable of burning the fuel in an internal combustion engine, but current development in the industry is focused on fuel cell/electric technology.
Hydrogen is certainly an interesting technology for the future but it’s unlikely to be the obvious choice for most people looking for a new business car to lease or to buy with the specialist infrastructure required although there is a steady programme of new hydrogen fuelling stations, encouraged by government grant incentives.
But more manufacturers are getting involved. At the 2017 Frankfurt Motor Show, Mercedes launched the new GLC F-cell, the first hydrogen fuel cell car that is also a plug-in. The GLC F-cell is capable of covering up to 30 miles in electric-only mode.
What are the advantages of electric cars?
Simplicity and convenience
The basics of electric cars are very simple. The main driving controls are the same as in a petrol or a diesel, with accelerator and brake and the usually a single fixed ratio transmission controlled in a similar way to an automatic via a standard “P-R-N-D” gate.
However one of the key features, especially with energy regeneration from brakes, is that simply lifting off the accelerator will create quite effective ‘braking’ so no ‘coasting’ up to traffic lights or you’ll stop short!
Iin practice, it’s more to do with modulating the accelerator pedal, lifting it off gently to get the right rate of deceleration under regen, rather than just treating the accelerator pedal as an on-off switch.
Nissan is taking this a stage further on the latest Leaf with an e-Pedal that allows drivers to start, accelerate, slow down and stop, simply by increasing or decreasing the pressure on the accelerator – although it is still necessary to use the brake pedal in the normal way for an emergency or sudden stop.
Forget comparisons with golf buggies or milk floats – electric cars are quick, especially in terms of initial acceleration.
A petrol or a diesel needs a bit of time to build up the engine revs at which maximum torque or maximum power are produced but an electric motor delivers most of its shove instantly from the moment it starts turning, so an electric car will always be quick away from the lights and squirting into spaces in traffic around town.
The other side of the coin is that some models run out of puff slightly at higher speeds and many are limited to 80-90 mph, partly in the interests of economy – although that shouldn’t be too much of a problem in UK conditions.
More expensive electric cars, such as the Teslas, are among the fastest vehicles on the road and are capable of besting many specialised traditional high-performance models.
This is one of the most noticeable differences between electric cars and their petrol and diesel counterparts. Electric motors are exceptionally smooth and near-silent at lower speeds, although there’s usually a quiet whine as the revs pick up.
With low levels of what people in the motor industry call NVH (noise, vibration and harshness), travelling in an electric car is probably more relaxing and less fatiguing than travelling in a petrol or a diesel one.
One effect of having a quiet electric motor is that other sources of noise – for example, road noise – assume greater prominence. And the refinement of an electric car is a great leveller – all electric cars, cheap or expensive, share this quietness and are smoother than all but the most luxurious petrols and diesels.
Low cost per mile
Electric cars have much lower fuel costs than even the most economical petrols and diesels – a commonly-used rule of thumb is that they cost 2p per mile when topped up from the domestic mains compared with (very roughly) 10-20p for cars with internal combustion engines.
Charging from public charging points will often be more expensive but most electric car charging still takes place at home.
Low servicing and maintenance costs
No exhaust emissions
Electric cars are cheaper to maintain than petrols or diesels – the basic design has fewer parts and there are far fewer service items. Nobody will ever have to change oil, spark plugs, filters or an exhaust on a pure electric car. Regenerative braking via the electric powertrain means the brakes have to do far less work in an electric car as well.
A pure electric car has no tailpipe emissions. That means it’s good for the air quality in polluted urban areas – one of the reasons electrics are so heavily favoured by current government policy and enjoy concessions in connection with, for example, the London Congestion Charge.
While some of the fiscal incentives for electric cars have been tightened up they are still fairly generous. New electric car prices are reduced via a plug-in car grant, and electric cars attract no VED unless they are priced over £40,000 when they incur the £310p.a. premium surcharge in years two to six, as introduced for new cars registered from April 2017.
Cars registered before then are duty free!
Hybrids only get a £10 reduction on the £140 standard rate VED.
Electricity from the mains isn’t taxed anything like as heavily as petrol or diesel at the pump, and certain aspects of the company car taxation regime favour electrics as well – particularly company car tax from 2020/2021 when zero emission cars will be taxed at a new 2 per cent rate.
What are the disadvantages of electric cars?
Higher cost to access the technology
Electric cars are cheaper to run than petrols or diesels, but they are usually more expensive to lease or buy in the first place. How much more is less clear. Direct comparisons are difficult, not least because electric cars and others don’t really offer the same things.
Most petrol and diesel cars offer a range between top-ups that owners of most electric cars can only dream of, but on the other hand, the real world performance and refinement of even the cheapest electric cars is a match for more expensive cars with internal combustion engines.
One thing is certain, though – a number of studies have shown that the cost of making electric cars and their batteries is coming down so the initial price disadvantage of electrics won’t be with us forever.
One other thing to look out for – on many Renaults and Nissans, the traction battery may be included in the price of the car or can instead be leased separately. That means a lower initial price that is offset by the need to pay a monthly rental for the use of the battery.
On a Renault Zoe the monthly battery rental ranges from £49 for up to 4,500 miles per year to £110pm for unlimited mileage.
The Renault Zoe and the Nissan Leaf are available in both “batteries included” and battery lease versions, and it is important to establish the status of a particular car’s battery before making any decisions.
Limited range on early/cheaper models
Most of the early versions of the current crop of electric cars had very limited range compared with their petrol and diesel counterparts – an average of about 80 miles on a single charge. Journalists quickly coined the term “range anxiety” to describe the fear of running out of juice on these early models.
But the battery capacity – and with it the range – of most mainstream electric models has been increasing quite quickly. The Nissan Leaf, Renault Zoe, Volkswagen Golf and BMW i3 are now all available with much bigger batteries than when they were first launched a few years ago, and in the case of the Zoe, the optional larger-capacity battery is almost twice as big as the original standard battery.
This means that most of these cars are now capable of achieving a range in the 150-200 mile bracket, with the new Leaf up to an official 235 miles, at least according to the official New European Driving Cycle (NEDC) test. This range is still not as good as a petrol or a diesel, but a very big improvement in the space of just a few years.
Battery capacity is measured in kiloWatt hours (kWh). The first Nissan Leafs had a 24 kWh battery and a later upgrade took this to 30 kWh. The second-generation Leaf is being launched with a 40 kWh battery with the promise of more to come in 2018, while a competitor that is not coming into the UK, the Chevrolet Bolt, is already being sold with a 60 kWh battery.
Teslas were fitted with larger capacity battery packs from the beginning and have always offered a maximum range that has been much more competitive with internal combustion engined cars.
Charging your electric vehicle
Most electric vehicles are charged by their owners at home, but for this it is essential to have off-street parking close to your power supply.
Home charging is a convenient but time consuming process, and most owners charge their cars overnight. Some electric cars can be charged via a 3-pin socket but this is not usually recommended as a long-term solution for regular use. Extension leads must never be used.
Most electric car owners have a dedicated home charger that will top up the battery pack more quickly than a normal three-pin wall socket, although the process will still take several hours and is normally carried out overnight. This is usually described as fast charging, especially if the charger is capable of 7kW or more.
Typical installations are 3.6 kW, which Pod Point, a leading supplier, says is 1.6 times faster than a three-pin plug, or 7 kW (three times faster). Pod Point also offers a 22 kW charger (ten times faster) but this requires a three-phase electricity supply.
Domestic chargers used to be offered free to registered keepers of plug-in cars but the government subsidy is now fixed at £500, meaning a net cost to the customer of a few hundred pounds.
While there are several different charging technologies, which each use different sorts of cables and connectors, for home charging you don’t normally need to worry about compatibility problems because most cars can be charged using a loose cable into the standard “type 2” wall socket which is usually used by home chargers.
For longer journeys, electric car owners will have to rely on public charging infrastructure, which varies enormously.
Tesla has its own network of rapid (as opposed to “fast”) “Superchargers” and the main UK motorways are also well covered with rapid charging facilities, particularly those provided by Ecotricity.
Rapid chargers will usually use a cable that is tethered to the unit, rather than the loose cable that is normally used for home charging. Here the differences between the different charging standards – for example CHAdeMO (CHArge de MOve) which has its origins in Japan, and CCS (Combined Charging System), which tends to be favoured by the European manufacturers – are important, and the connectors at the “car” end vary.
Rapid chargers operate much more quickly than even the fastest home chargers, and allow an electric car to take on a big charge in the time it takes to down a quick coffee, but the situation is much more hit-and-miss elsewhere and journeys may require careful planning.
Several public charging points, typically those in locations such as supermarkets and hotels are “fast” rather than “rapid” and are much more similar to the dedicated charging points owners will have at home.
Of course, PHEV owners need to remember both to plug their cars in at night and make the occasional visit to a filling station to top up the liquid tank.
Unknowns on durability – e.g. battery life
Some prospective buyers are wary of the unfamiliar technology contained in electric cars. The battery pack represents a large proportion of the value of an electric car, so buyers will inevitably ask how this major component will perform over the life of the car.
Even the earliest modern electrics are less than half-way through the typical roughly 14-year life cycle for cars in the UK but the early tentative conclusion seems to be that while battery performance can drop off a little this deterioration isn’t turning out to be a big problem.
A number of manufacturers provide a separate, longer, warranty for their cars’ battery packs – for example, the battery pack in the 30kWh version of the Nissan Leaf is covered against capacity loss of more than 25 per cent for eight years or 100,000 miles.
It’s quite important to consider every use to which you might put an electric car and check its capabilities and specifications carefully.
For example, electrics and hybrids often have very low permitted towing weights, perhaps because the manufacturers did not expect early shorter range cars to be put to this use rather than because of any inherent limitations in the technology.
There are exceptions, though – the Tesla Model X, for example, has a generous towing capacity of over 2,000 kg, while Volvo’s V60 plug-in hybrid can pull 1800 kg.