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

Standing at the pump, many drivers ask the same question: should you use unleaded petrol or pay extra for super unleaded?

Both fuels work in petrol cars, but they are not interchangeable in terms of performance, cost, or manufacturer recommendation.

The difference comes down to octane rating, ethanol content, and how the engine is designed to use fuel. Choosing the wrong one usually does not damage the car, but it can affect cost efficiency and performance in specific engines.

What Is Unleaded Petrol?

Unleaded petrol is the standard petrol used in the UK.

It is typically:

• 95 RON fuel

• E10 petrol (up to 10% ethanol)

• Designed for most petrol cars

• Available at every UK fuel station

Most modern petrol cars, including those used in personal car leasing deals are built to run efficiently on 95 RON unleaded.

Is Unleaded Petrol the Same as Petrol?

Yes. In the UK, “petrol” normally refers to unleaded petrol. Leaded petrol has been phased out completely.

Is Unleaded Petrol Petrol or Diesel?

Unleaded is petrol, not diesel. Diesel is a separate fuel type with different combustion properties and must not be mixed.

What Does Unleaded Fuel Mean?

It means petrol without lead additives. Lead was removed due to environmental and health regulations, making unleaded fuel the UK standard.

Is Unleaded Petrol 95 or 97?

Unleaded petrol is 95 RON. Super unleaded starts at 97 RON and can go up to 99 RON.

What Is Super Unleaded Petrol?

Super unleaded petrol is a higher octane premium fuel.

It is usually:

• 97–99 RON

• E5 petrol (lower ethanol content)

• Sold as premium branded fuel (Shell V-Power, BP Ultimate, Tesco Momentum 99)

What Does Super Unleaded Mean?

It means the fuel is designed to resist knocking at higher compression, which benefits certain engines.

Is Super Unleaded Petrol E5?

Yes. Most super unleaded petrol in the UK is E5, meaning it contains up to 5% ethanol.

Unleaded vs Super Unleaded Petrol: Key Differences

Octane Rating (Main Difference)

• Unleaded: 95 RON

• Super unleaded: 97–99 RON

Higher RON does not automatically mean better fuel for all cars.

E10 vs E5 Fuel

• Unleaded petrol: usually E10

• Super unleaded petrol: usually E5

E5 is often preferred for older engines or specific manufacturer requirements.

Performance Difference

If your car is designed for 95 RON:

• No meaningful performance gain from super unleaded

If your car requires premium fuel:

• Better combustion stability

• Smoother acceleration

• More consistent engine response

Fuel Economy

Some drivers see small improvements with super unleaded, but results depend heavily on:

• Engine type

• Driving style

• Journey length

For most standard vehicles, savings are minimal.

Cost Difference

Super unleaded is usually 10–15p per litre more expensive.

Over a full tank, this becomes a noticeable cost difference, especially for high-mileage drivers or fleet users.

Which Petrol Is Best for Your Car?

This is one of the most searched GSC queries and depends entirely on manufacturer guidance.

Use Unleaded Petrol If:

• Your car is designed for 95 RON

• You drive a standard petrol car

• You use a hybrid petrol vehicle

• You drive a leased everyday car

Use Super Unleaded If:

• Your manufacturer recommends 97–99 RON

• You drive a performance petrol car

• Your engine is high compression or turbocharged

• You have an older car requiring E5 fuel

For drivers using business car leasing deals UK or personal lease cars, following the manufacturer fuel requirement is the safest way to avoid unnecessary running costs.

Can You Mix Unleaded and Super Unleaded?

Yes.

You can safely mix both fuels.

Modern engines automatically adjust ignition timing and combustion behaviour, so mixing does not cause damage.

You may mix:

• When topping up with a different fuel grade

• When switching between fuel stations

• When super unleaded is not available

Only avoid mixing if the manufacturer explicitly requires continuous premium fuel use.

Unleaded vs Super Unleaded: What Happens If You Use the Wrong One?

If You Use Super Unleaded in a Normal Car

• No damage

• Minimal or no performance change

• Higher fuel cost only

If You Use Unleaded in a Premium Fuel Car

• Engine may adjust automatically

• Slight performance reduction possible

• Long-term use not recommended if premium is required

E5 vs E10 Petrol Explained

What Is E10 Petrol?

• Contains up to 10% ethanol

• Standard UK unleaded fuel

• Compatible with most petrol cars

What Is E5 Petrol?

• Contains up to 5% ethanol

• Used in super unleaded fuel

• Required for some older vehicles

If unsure, check your fuel cap or handbook.

Types of Petrol in the UK

• Unleaded petrol (95 RON, E10)

• Super unleaded petrol (97–99 RON, E5)

• Premium branded petrol (additive-enhanced versions of super unleaded)

All fuels meet UK fuel quality standards.

What Petrol Should I Put in My Car?

Car Type	Recommended Fuel
City car	Unleaded 95 RON
Family car	Unleaded 95 RON
Hybrid petrol car	Unleaded 95 RON
Performance car	Super unleaded
Older petrol engine	Super unleaded (E5)

If you drive a lease car, always follow the manufacturer specification rather than fuel price alone.

Fuel Costs in the UK

Super unleaded is typically 10–15p per litre more expensive than standard unleaded.

For drivers doing higher mileage or running company vehicles, this difference can significantly affect monthly fuel spend.

Also Check: Fuel Cost Calculator

The Simple Rule

Use unleaded petrol unless your manufacturer specifically recommends super unleaded.

Higher octane does not automatically improve performance in standard engines.