Super Unleaded vs Unleaded Petrol: Which Fuel Should You Use in UK?

If you’ve ever stood at a petrol pump wondering whether to fill up with unleaded or super unleaded, you’re not alone. Both fuels look the same, both work in petrol cars, yet they’re priced differently, leaving many drivers asking if the more expensive option is really worth it.

Let’s break down the difference between unleaded and super unleaded petrol, how each affects your car, and when spending extra might actually make sense.

What Is Unleaded Petrol?

Unleaded petrol is the standard petrol sold at most UK forecourts. It’s also known as E10 fuel and usually has a 95 RON (Research Octane Number) rating. This fuel is designed for the majority of modern petrol engines.

The term unleaded simply means it doesn’t contain lead additives, which were phased out due to environmental concerns and engine health. Almost every car built after 1992 runs perfectly fine on regular unleaded petrol.

Quick facts:

• Octane rating: 95 RON

• Label at pump: E10

• Suitable for: Most petrol cars and small engines

• Typical use: Everyday driving, short trips, and mixed journeys

What Is Super Unleaded Petrol?

Super unleaded petrol, often labelled E5, has a higher octane rating of 97 to 99 RON, depending on the brand. You’ll see names like Shell V-Power, BP Ultimate, or Esso Synergy Supreme+.

That higher octane number means the fuel can handle more compression before igniting, which is useful for high-performance engines, turbocharged cars, and older vehicles designed for premium fuels.

Quick facts:

• Octane rating: 97–99 RON

• Label at pump: E5

• Suitable for: Performance or older engines

• Typical use: Motorway driving, performance tuning, long-distance trips

Difference Between Unleaded and Super Unleaded Petrol

Octane Rating Explained (RON 95 vs RON 97/99)

The octane rating measures how well a fuel resists “knocking,” which is premature ignition inside the engine.

• Unleaded (95 RON) works perfectly for most cars designed for regular petrol.

• Super unleaded (97–99 RON) provides better protection in engines with higher compression ratios.

Cars that require premium fuel will clearly state this inside the fuel cap or owner’s manual.

Engine Performance and Fuel Economy

If your car isn’t tuned for high-octane petrol, switching to super unleaded won’t deliver noticeable performance gains. However, for engines built to take advantage of it, drivers often report:

• Slightly smoother acceleration

• Improved throttle response

• Marginally better fuel economy on long runs

Is Super Unleaded Worth It?

It depends on your car and driving style.

For most everyday cars, like a Ford Fiesta, Hyundai i10, or VW Golf, regular unleaded (E10) is absolutely fine.

But if you drive something performance-oriented, such as a BMW M-Series, Audi S-Line, or Mercedes AMG, using super unleaded petrol can help the engine perform as intended.

When it’s worth the extra cost:

• You own a high-performance or turbocharged petrol car

• You drive long distances regularly

• You’re concerned about keeping carbon build-up low in older engines

Can You Mix Unleaded and Super Unleaded Petrol?

Yes, you can safely mix the two. Your car’s ECU (engine control unit) automatically adjusts to the blend.

For example, if you usually fill up with regular unleaded but only have super unleaded available, topping up won’t cause any problems. You’ll just have a slightly higher average octane mix, which your engine can handle easily.

However, it’s not recommended to consistently mix fuels if your manufacturer specifically recommends premium petrol. Always follow their guidance for best performance and warranty protection.

Which Petrol Is Best for Your Car?

If you lease your vehicle, it’s always best to check the fuel recommendations in your handbook before filling up.

Petrol Types and Grades in the UK

The UK currently offers the following petrol grades:

• E10 petrol: Up to 10% renewable ethanol content, 95 RON

• E5 petrol: Up to 5% ethanol, 97–99 RON

• Premium fuels: Branded options like BP Ultimate, Shell V-Power, Esso Supreme+

Each grade meets UK government standards for emissions and performance.

E5 vs E10 — What You Need to Know

From 2021, E10 became the standard unleaded petrol in the UK. It’s cheaper and more sustainable but can cause issues in some older vehicles.

If your car was built before 2011, check its compatibility using the government’s E10 vehicle checker before filling up.

Petrol Costs in the UK (as of October 2025)

That’s a difference of around £6–£7 per full tank, which is noticeable over time. If you drive 10,000 miles a year, the choice of fuel could impact annual costs by roughly £85–£105 depending on driving efficiency.

Switching to Electric — The Cost-Saving Alternative

If you’re trying to save on fuel altogether, electric car leasing is becoming one of the most practical choices. With no petrol costs, fewer maintenance expenses, and access to low-emission zones, it’s worth exploring.

The difference between unleaded and super unleaded petrol mainly comes down to octane rating and engine design. For most UK drivers, unleaded petrol (E10) is efficient, reliable, and cost-effective.

However, if your car manual recommends higher octane fuel or you’re leasing a performance car, super unleaded petrol can deliver smoother performance and long-term engine protection.