PHEV vs EREV
It’s now over a decade since electric cars and their plug-in equivalents made their first real breakthrough into the market, but there’s still plenty of confusion over how those that use combined drivetrains work. Craig Cheetham explains the difference be
Are Plug-in Hybrids better than Range Extenders? What’s the difference between these two types of propulsion?
Make no mistake, alternatively fuelled cars have taken a big step beyond being a gimmick that’ll never catch on – a spectre that has haunted the electric car ever since the first EV pioneers plugged their wares over a century ago.
Back then, it was electricity versus internal combustion in a race to popularise the car itself, and in the birth years of motoring the two were seen as realistic rivals. But as the internal combustion engine grew in capacity and number of cylinders, it soon became apparent that combustible fuels were by far the most practical option, with a greater range and more efficiency. Electric cars were easier to maintain, but also much more likely to leave their owners stranded when they ran out of juice – a fear that in latter years became known as ‘range anxiety’ – a phrase that was allegedly invented by General Motors and used to great effect to steer people towards its range-extending Volt.
Indeed, the Volt is widely cited as the car that saved General Motors. It was announced for production just before GM filed for bankruptcy protection after the global financial crisis and was seen as proof that the giant company had a future that involved more than just cashing in on big trucks.
It’s ironic, then, that the technology that effectively saved the company is now seen as a minority option. It was an idea that seemed almost faultless at birth: a car that was to all intents and purposes fully electric, but which had a secondary power supply should it need it so you could travel longer distances if required; a car that would dispel the ‘range anxiety’ that put so many people off buying an EV in the first place yet offered them the same emissions-free motoring and taxation benefits; and an idea that was, in essence, so much cleverer than the plug-in hybrids (PHEVS) that followed.
But what’s the difference between the two, why is PHEV so much more of a commercial success, and is it really the best option for the future, with the sale of petroland diesel-only cars set to be outlawed from the middle of the next decade?
How do they work?
To the uninitiated, a plug-in hybrid electric vehicle (PHEV) and an extended range electric vehicle (EREV) appear to be essentially the same thing. But while the basic logic is the same – a car that you can plug in and run on pure electricity, with an internal combustion engine to sustain itself when it runs out of battery power – the way in which that technology is deployed is different. And it’s all to do with the way the car transmits its power to the road.
Why is PHEV so much more popular?
In a nutshell, it’s much cheaper.
The tax incentives for owners and manufacturers of both types of vehicle are broadly similar, but for manufacturers it’s much simpler to install a compact electric drivetrain around existing petrol or diesel architecture than it is to create a full EV platform and then install a petrol engine.
The BMW i3 is different in that it was designed from the ground-up to be a pure electric model, with the range-extender model joining the range as an option for those who occasionally needed the extra range, while the Volt/ampera and London Taxi were both planned as EREV vehicles from the outset.
It’s arguably the better idea, but for volume production it costs a lot more to produce. If the volumes were there right now, EREV would be more viable – but it’s an expensive technology and that price ultimately has to be passed on to consumers. Hence, PHEV is the marketleading technology by some margin. But as other manufacturers come on stream with EREV tech (Taxi manufacturer LEVC, for example, is owned by Chinese industrial giant Geely, which also owns Volvo) EREV cars could well become more popular in the fullness of time.
Maintenance and reliability
So far, both EREV and PHEV cars have shown a good reliability record, but that’s hardly surprising because they’re both relatively new to the market.
But as the number of EVS grow, it will be interesting to see how they hold up as they rack up the miles.
In reality, it’s likely that PHEV cars will demonstrate a similar reliability record to ‘normal’ internal combustion engines because they use the same basic technology. The electric components are general low maintenance and don’t require servicing, though battery life will be a big question mark long-term. That said, most manufacturers guarantee the battery for a minimum of eight years, and in practice full EV models such as the Nissan LEAF have now been on sale
for 10 years without a huge amount of battery deterioration, which augurs well for long-term dependability.
EREV cars are likely to be even more reliable, because the petrol engines fitted to them rarely run quicker than at a fast idle, meaning they don’t suffer from excessive wear. In addition, they tend to be warm before they’re started up, so there’s unlikely to be much premature wear from cold oil and coolant paths. Indeed, the engine fitted to the Chevrolet Volt and Ampera is actually blindingly simple – a Vauxhall 1.4-litre unit as found in many a Corsa and Astra over the years.
In addition, the electric motors and drivetrains are low maintenance, requiring only regular lubrication so, other than the usual braking and suspension service items, they have the potential to offer superb long-term reliability, though the battery life in service is the
big question. That said, after 10 years of use, the vast majority of Chevrolet Volts in the US are going strong, with no signs of severe battery depletion.
Should I buy one – and what should I look for?
The million dollar question is not if you should buy a PHEV or EREV, but when should you buy one, because when conventional petrol and diesel engines are outlawed in 2035, we’ll all need an alternative fuel car of some type - at least when the stocks of internal combustion cars start to dry up.
Until recently, nearly all PHEVS and EREVS have been bought new, but there are now quite a few filtering on to the used market and – unsurprisingly – they hold their value very well, so don’t go out looking for one expecting a bargain.
The key is to analyse your weekly driving patterns and work out how far you travel, and how much of it could be done on electric only. Then establish how long it would take you to make a cost saving. Access to charging points is also a major point – one of the key barriers to EV adoption is that people with on-street parking don’t have a realistic way of owning one unless there are charging points provided locally or at work – something that the government doesn’t appear to have thought through in detail ahead of the forthcoming new legislation.
But on the plus side, the electric car infrastructure is better than it ever has been and is improving all the time, and it’s only going one way.
Other than general wear and tear checks, you need to ensure that any plug-in vehicle – a PHEV especially – has an up-to-date service record, but in the long-term don’t be put off carrying out the day-to-day maintenance yourself. Brakes, suspension and the internal combustion engine are largely the same as they’ve ever been.