New 2030 ban on petrol and diesel cars: what it really means

Until recently, a total ban on the sale of new petrol and diesel cars, including hybrids, had been expected to come into effect in 2030. However, partly fossil-fuelled cars were given a stay of execution at the start of April when the government announced that new hybrid cars can continue to be sold after 2030, before being banned from 2035 onwards.

We explain what the new rules mean for your next car and, with our exclusive fuel consumption data, your wallet.

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What is the 2030 ban and what’s changed?

Although there will still be a ban on new petrol and diesel cars in 2030, the most sweeping changes have been delayed by an extra five years.

The government has also made changes to what vans can be sold and when, but for this article, we’re sticking to cars. 

What’s banned from sale after 2030?

• New pure fossil fuel cars
• New fossil fuel mild hybrids (with a small battery providing a power boost)

What’s allowed after 2030?

• Fossil fuel full hybrids (with a mid-sized battery with an EV-only mode for short distances at speeds of around 30mph, charged solely by the engine or brakes, such as the Toyota Corolla)
• Fossil fuel plug-in hybrids (with an EV-only mode that can power the car at motorway speeds for between 20 and 60 miles, charged at the wall and by the brakes or engine, such as the VW Golf GTE).
• Electric cars

What’s allowed after 2035?

• Electric cars

The shift from only allowing the sale of new EVs to also allowing new hybrids is the biggest change to this policy since it was first announced by the Theresa May Conservative government in 2017. 

What does it mean for me?

If you were dreading the thought of having to think about battery capacity and range anxiety, you won’t have to worry for another decade (unless the current or a future government makes further changes) and even then, only if you choose to buy new rather than used.

That’s because both full hybrids and plug-in hybrids can be driven in exactly the same way as a standard petrol or diesel car without hybrid tech, and your range will be limited – for the most part, by the amount of petrol or diesel in your tank.

Of course, to get the best out of the efficiency gains that hybrid motoring can offer, you would be best advised to adapt your driving style at the very least, but once you’ve bought your car, you’re free to drive it how you wish. This could have a detrimental effect on fuel economy on plug-in hybrids in particular, which we’ll get onto later. 

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Will it make cars greener from 2030?

Potentially, but since the government hasn’t released any specifications as to exactly what sort of hybrids will be allowed (aside from the broad categories of full hybrids and PHEVs), it’s really hard to know.

The short version is that full hybrids and fully-charged PHEVs are much more efficient when driving in town, but the advantages get smaller the further they’re driven, particularly on faster roads. Faster roads make up a greater proportion of miles driven in the UK, which puts a dent in the improved efficiency promised by the new hybrid rules. 

We can look at the current crop of full hybrids and PHEVs to get a picture of how this law change might affect fuel economy going forward, but until the government announces specifications, we have to base our predictions on the current state of the market.

Based on averages of petrol-powered cars available to buy new and their performance in our combined mpg test (a simulated 62-mile route including city driving, motorways and country roads), it’s clear that pure petrol cars are the least economical, on average, followed by mild petrol hybrids, full hybrids and plug-in hybrids. The picture is broadly similar when looking at their exhaust pipe CO2 emissions (grams per kilometre).

For the purposes of comparison, we’ll stick to comparing petrol-powered cars as it is the most popular type of fuel, although you can see the data we have on diesels in the graphs on this page.

Average mpg of cars available to buy new:

Which? combined 62-mile drive cycle mpg/emissions test data, based on 30 mild petrol hybrids, 14 mild diesel hybrids, 80 pure petrol cars, 60 pure diesel cars 45 petrol full hybrids and 48 petrol PHEVs available to buy new as of April 2025.

Average CO2 emissions of cars available to buy new:

Which? combined 62-mile drive cycle mpg/emissions test data, based on 30 mild petrol hybrids, 14 mild diesel hybrids, 80 pure petrol cars, 60 pure diesel cars 45 petrol full hybrids and 48 petrol PHEVs available to buy new as of April 2025. 

If, as per the ban, you eliminate the two least-economical categories of engine (petrol and diesel), the average miles per gallon goes up.

So does this mean cars will become more economical and thus better for the environment? Yes, but it’s more complicated because when you look at long-distance motorway driving, a different picture emerges.

Motorway driving eviscerates efficiency gains

According to the RAC Foundation, 65% of miles driven in the UK are on major roads (A-roads and motorways). Based on this, the fuel economy of a car at high speeds has a greater sway over its efficiency and emissions. 

Pure petrol cars, full hybrids and mild hybrids are roughly equal (35-37mpg between them) on motorway mpg, which means when it comes to motorway driving, allowing full hybrids to continue being sold past 2030 will open the door to fairly inefficient cars continuing to be sold for long-distance driving. 

Motorway mpg by engine type: 

Which? test data, based on 30 mild petrol hybrids, 14 mild diesel hybrids, 80 pure petrol cars, 60 pure diesel cars 45 petrol full hybrids and 48 petrol PHEVs available to buy new as of April 2025. Assumed average EV range of PHEVs: 32 miles. 

Plug-in hybrids have an average electric-only range of 32 miles. While this doesn’t mean the end of a journey, it does mean that the rest of your journey will be powered purely by the fossil fuel engine in your car. And that’s bad news since petrol PHEVs are less efficient than even pure petrol cars when driven with an empty battery, and it’s at its worst on motorways, averaging just 32mpg. 

In the best-case scenario, where you start your journey from the motorway slip road, you’ll get 32 miles of fuel-free driving before switching to the petrol engine, so it would take around 300 miles of motorway driving in this average PHEV before it became less efficient than a pure petrol car. But that is making optimistic assumptions about your PHEV’s current state of charge and where you actually started your journey. 

But driving in town will be much greener

It’s not all bad news. For the slow-speed urban driving many of us deal with day-to-day, full hybrids and plug-in hybrids are ideal. In our tests, pure petrol cars manage 39.5mpg in town, while mild hybrids manage 43.2. For full hybrids, this rockets up to 63.2 and, assuming you are driving in electric mode, PHEVs use no fuel over short urban journeys (a figure of 45mpg is the average if you don’t charge the battery).

Urban mpg by engine type: 

Which? test data, based on 30 mild petrol hybrids, 14 mild diesel hybrids, 80 pure petrol cars, 60 pure diesel cars 45 petrol full hybrids and 48 petrol PHEVs available to buy new as of April 2025. Assumed average EV range of PHEVs: 32 miles. 

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The issue of depleted PHEV batteries

Unlike EVs, where you have to charge them to keep moving, PHEVs will keep on going even if you’ve let the main battery run flat. This is particularly pertinent given that, if you can’t charge at home, charging a car’s battery at a public charging point is often as expensive as filling up with the equivalent amount of fuel (on average). 

So if you can’t charge at home, you may feel less motivated to charge your car at all, especially given most PHEVs can only be charged at slower AC chargers and are thus pretty slow, expensive and inconvenient to charge unless you have a kerbside charger near your home. What’s more, the electric motors in PHEVs are about 20% less efficient than those in EVs on average, so they cost more to charge per mile driven. It might seem more convenient to leave the battery empty and use petrol all the time. 

Electric motor efficiency in PHEVs and EVs:

Based on 49 PHEV and 107 EV models available to buy new as of April 2025. 

But the fuel consumption and environmental consequences of doing this aren’t great, as you’re effectively lugging around a hefty battery and electric motor, both of which are doing nothing aside from weighing you down. A PHEV with an empty battery is about as efficient as a pure petrol car in town and on country roads, and even less efficient on motorways.

Expert View: What will we be buying in 2030?

Michael Passingham
Which? Senior Researcher

All the above analysis is based on the current state of the car market. With more certainty about what they’ll be allowed to sell here in the UK, I’d expect manufacturers to start offering more PHEVs in their ranges, along with more full hybrids. That leaves Toyota and Lexus in a particularly good position as the bulk of their ranges are already made up of full hybrids and EVs (as well as a hydrogen car), but most manufacturers offer at least a handful of full hybrid and PHEV options but often at a hefty price premium vs pure fossil fuel and mild hybrid cars. For example, the super-cheap Dacia Duster full hybrid is about £3,000 more expensive than the mild hybrid version. All manufacturers will likely have to work on getting the price of these cars to a more affordable price.

The Society of Motor Manufacturers and Traders, which represents UK car brands and dealers, has been broadly welcoming the loosening of restrictions on what can be sold from 2030 onwards, citing economic headwinds and UK manufacturing competitiveness as key influencers over whether the UK car industry can stay fiscally sustainable. When I asked, it didn’t have a public view on what sort of efficiency requirements the government should put in place; it said to check with the government.

We did exactly that, and the government told us it expected experts to provide more information on what will be allowed ‘in the next few months’. The government also said in its announcement that it would be pushing forward with tax breaks on EVs to help people switch, but this hasn’t been detailed yet either, and it didn’t specify whether this would be on the costs of public chargers, the cars themselves, or both.

Will the government set efficiency and emissions targets so the environmental picture improves compared to the current range of hybrids and PHEVs? Those concerned about the ecological impact of personal motoring will certainly hope so, but given car manufacturers work at glacial timescales, getting their hybrids to be more efficient by 2030 (and only for five years' worth of sales) is going to be a challenge. Thus, the picture today may well be pretty reflective of the picture in 2030.

Additional reporting from Dino Buratti.

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