Hybrid cars are billed as an environmentally-friendly stepping stone towards cleaner travel, but are they as green as they seem?

Road transport accounts for 22% of the UK’s total CO2 emissions – a major contributor to climate change. In a bid to slash this figure and keep the UK on track to hit its Paris Climate Agreement commitments (to limit global temperature increases to 1.5°C), the government will ban the sale of new petrol and diesel vehicles by 2030 – a move it hopes will encourage people to take up electric vehicles (EVs) instead.

In between the traditional combustion engine car and the EV lies the hybrid car. Touted as a greener alternative to petrol and diesel, hybrid cars are often advertised as an eco-friendly bridge to cleaner personal transport. But as reports suggest they don’t quite live up to the hype and the government remains unsure how to phase them out, some parties say these claims are simply greenwash. Here’s what you need to know about how green hybrids actually are.

What is a hybrid car?

In simple terms, a hybrid vehicle is a cross between a regular petrol or diesel car and an electric vehicle. There are two types of hybrids.

Hybrids:
These vehicles use an electric motor to drive the wheels, although this is usually only for very short distances – no more than a mile or two. Their limited electric range is a result of their small batteries, which recharge during braking or by collecting energy directly from the engine itself.

Plug-in hybrids (PHEVs):
The batteries in these vehicles are much larger than those in full hybrids, so they need to be charged via a cable when parked (like an EV). The latest PHEVs can offer up to 30-40 miles of electric-only range, so short journeys can be completed without using the engine or fuel.

What costs are involved with a hybrid car?

Because of the advanced technology, PHEVs generally come at a premium, although drivers can expect to pay lower fuel bills in the long run.

According to Auto Express, the cheapest full hybrid car on the market right now is the Toyota Yaris Hybrid, at £19,910. The cheapest PHEV, meanwhile, is the Hyundai Ioniq Plug-in at £30,250, so you can see the base cost differences involved.

Since full hybrids don’t offer any meaningful electric range, running costs are generally focused on PHEVs only in comparison with EVs and combustion engine cars. Exact running costs will of course vary between makes and models, but DriveElectric gives the following examples (where ‘fuel’ is the price of electricity or petrol/diesel):

Vehicle                               Fuel cost per mile

Mini Electric                        3.9p
Mini PHEV                           8.7p
Mini 1.5 litre petrol             13p

VW ID.3 (EV)                        3.7p
VW Golf PHEV                        8p
VW Golf 1 litre petrol          12p

On the face of it, then, PHEVs stand to save drivers a reasonable chunk of money in running costs. However, it’s important to remember that these figures are based on optimal running conditions – we’ll come back to this later.

How do manufacturers claim that hybrid cars are green?

Since PHEVs are able to drive for up to 40 miles using electricity only, they are responsible for fewer emissions from traditional petrol/diesel consumption. As Next Green Car says:

“When in electric-only mode, hybrid cars charged using average UK 'mains' electricity show a significant reduction in CO2 – the figures suggest a reduction of around 40% compared to an small petrol car (tailpipe 130g CO2/km). Renewable electricity reduces fuel life cycle emissions to almost zero.”

In official lab tests, PHEVs are said to emit 44g CO2 per kilometre. A small petrol engine up to 1.2 litres, meanwhile, will emit around 150g CO2 per kilometre, while a medium petrol engine of up to 1.8 litres will emit around 150-185kg of CO2 per kilometre.

What do critics say about hybrid cars?

The problem is, these green-looking figures are derived from very specific controlled lab testing with conditions that are almost impossible to replicate in normal everyday life. As such, according to campaign group Transport and Environment, PHEVs actually emit around 120g of CO2 per kilometre – much more than the 44g claimed by manufacturers.

There are a couple of reasons for this. Firstly, owners do not frequently charge their vehicles, so they end up being reliant on the combustion engine even for short journeys. As Next Green Car states, official tests assume PHEVs are operating on electric mode for around 80% of the time when it fact findings suggest they tend to be powered on electricity for fewer than half the miles driven.

Secondly, the report by Transport and Environment indicates that electric mode is often automatically shut off if the conditions are not suitable for the technology, and one of the issues is cold weather – something that has particular significance in the UK.

According to the report, popular models have been found to deviate from using their electric-only modes to the petrol engine when temperatures drop, even when the on-board battery is fully charged. This is partly because the batteries need to warm up in order for them to send power to the electric motors. Using features such as windscreen demisters and cabin heating can also cause a switch to petrol power.

What’s the government’s position on hybrid cars?

While the sale of new petrol and diesel cars will be banned from 2030, hybrids have been given a ‘stay of execution’ until 2035, although the criteria around this is yet to be decided. A consultation will be launched later in 2021 to decide the distance a new hybrid electric vehicle can travel on zero emissions in order to remain on sale from 2030 to 2035.

However, the government is keen to phase them out and encourage a full transition to EVs. In October 2018 ministers removed the £2,500 plug-in car grant for PHEVs after considering evidence that they were being used in an uneconomical way – many had bought PHEVs for businesses to benefit from lower tax rates. This led to an 18% drop in PHEV sales the following year, and the sale of pure electric models overtook PHEVs for the first time.

Do hybrid cars qualify for low emissions zones?

The roll-out of Ultra Low Emission Zones (ULEZs) and Clean Air Zones (CAZs) in cities across the UK is accelerating, and PHEV owners (or would-be owners) need to be mindful that plug-in hybrids do not automatically qualify for these areas just because they’re billed as ‘green vehicles’.

Two factors will determine whether you face a charge for entering these zones: how many emissions your vehicle produces and what type of vehicle it is. Birmingham’s Clean Air Zone, for example, stipulates that hybrid vehicles only qualify if the petrol or diesel part of the engine is compliant with Euro 4 or Euro 6 standards respectively.

In short, the only way to guarantee your vehicle is permitted in these zones without charge is to drive an electric vehicle, otherwise you will have to check local guidance.

Should I buy a hybrid car?

On the face of it, PHEVs are an attractive proposition, bridging the gap between petrol and electric in a way that’s convenient for those that want to be greener without some of the restrictions that pure EV-ownership still brings. However, as a raft of findings indicate, PHEVs aren’t necessarily as green as manufacturers would have you believe. It’s also worth bearing in mind that a PHEV is a big financial investment, and you only stand to benefit from reduced fuel costs if you use and maintain the vehicle correctly.

If you are currently in a position to buy a new vehicle but can’t commit to a fully-electric car, a PHEV could be the greener choice providing you keep it charged and understand its limitations around some features (such as window de-misting or cabin heating, as discussed above). However, if you have access to the right charging infrastructure, you’re better off getting ahead of the curve and committing to cleaner transport with an EV now – and you could be eligible for a grant too. Find out more about Plug-in Car Grants here.

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