E5 Cheaper Than E10? How to Get Super Unleaded for Less Than Standard Petrol

E5 super unleaded is supposed to cost more than E10 standard petrol. But at hundreds of forecourts across the UK, it doesn't. You can fill up with the higher-grade fuel and actually pay less than the E10 price down the road.

Wait — How Can Premium Petrol Be Cheaper?

It sounds counterintuitive, but it happens more often than you might think. The UK has over 8,000 forecourts, each setting their own prices. Supermarkets, independents and branded stations all compete locally, and their pricing does not move in lockstep.

The result: a supermarket's E5 super unleaded can easily undercut a branded station's E10 a mile away. An independent forecourt selling E5 at a thin margin can beat a motorway services E10 price by 15 pence or more. The "premium costs more" rule only holds when you are comparing the same station's two pumps — not when you compare across different stations in your area.

How Common Is This?

We analysed CMA fuel price data across thousands of UK forecourts. On any given day, in most postcode areas, there are E5 stations priced at or below the median E10 price for that area. In some regions — particularly where a supermarket sells super unleaded near expensive branded forecourts — the gap can be striking.

Our comparison tool automatically surfaces these opportunities. When you search for E10 prices, the "E5 for Less" column shows every nearby forecourt where super unleaded costs less than the typical E10 price in your area.

What You Actually Get with E5

When you find E5 cheaper than E10, you are not compromising — you are upgrading for free. Here is what E5 gives you over E10:

• Higher octane (97+ RON vs 95 RON) — smoother combustion, particularly noticeable in cars that can take advantage of higher octane fuel.
• Less ethanol (5% vs 10%) — ethanol contains less energy per litre than petrol. E5 delivers slightly more miles per litre, typically 1 to 2 percent better fuel economy.
• Better for older cars — some pre-2011 vehicles are not fully compatible with E10. E5 is safe for all petrol cars.
• Better for infrequent drivers — ethanol attracts moisture. If your car sits for weeks between drives, the lower ethanol content in E5 is kinder to the fuel system.

A Real Example

Imagine you search for E10 in your postcode and see these results:

In this scenario, two E5 stations are cheaper than two of the three E10 stations. The Costco E5 price beats BP's E10 by 5p per litre — that is £2.50 saved on a 50L tank, and you are getting better fuel. The Asda E5 still beats the BP and Shell E10 prices.

Why This Happens

Several market dynamics create these pricing inversions:

• Supermarket loss-leading — Asda, Tesco, Sainsbury's and Morrisons use fuel as a footfall driver. They price aggressively on all grades, including super unleaded, to get you into the store.
• Warehouse clubs — Costco sells fuel at near-wholesale margins. Their E5 price regularly undercuts the national average for E10.
• Branded station premium — Shell, BP and Esso charge a brand premium on all fuel types, including standard E10. Their E10 is often more expensive than a competitor's E5.
• Motorway services — motorway forecourts add 15 to 25 pence per litre. Almost any local E5 station will beat a motorway E10 price.
• Local competition gaps — in areas with fewer stations, some retailers price higher because drivers have limited alternatives. A supermarket E5 in a neighbouring area can easily undercut.

The Savings Add Up

Even a modest 3p per litre saving adds up over a year. If you fill up 50 litres every fortnight, that is £39 per year — and you are running on higher-octane, lower-ethanol fuel. When the gap is 5p or more, the annual saving reaches £65+.

And because E5 gives you 1 to 2 percent better fuel economy than E10 (due to lower ethanol content), you are stretching each tank slightly further too. It is a genuine win-win when the price is right.

How to Find E5 Cheaper Than E10

You do not need to check every forecourt manually. Our comparison tool does the work for you:

1. Go to the fuel price comparison page
2. Enter your postcode and select E10 (Unleaded) as the fuel type
3. Look at the "E5 for Less" column — these are E5 stations priced below your area's median E10 price
4. Each result shows the exact price, distance, and how much you save per tank compared to the E10 results

We also highlight "Cheaper E5 nearby" hints directly within each E10 station card, so you can instantly see whether there is a better-value E5 option close to the E10 station you are looking at.

Should You Always Switch to E5?

Not necessarily. The opportunity depends on your local market. Some postcodes regularly show E5 below E10 prices; others rarely do. The key points:

• If E5 is cheaper or the same price — absolutely fill up with E5. You get better fuel at a lower cost. There is no downside.
• If E5 is within 2 to 3p of E10 — it is still worth considering. The slight fuel economy benefit of E5 may close the gap entirely.
• If E5 is 10p+ more expensive — stick with E10 unless your car specifically requires higher-octane fuel. The price premium is too large for the marginal efficiency gain to offset.

Frequently Asked Questions

Is there any reason not to use E5 in my car?

No. E5 is compatible with every petrol car on the road. It was the standard fuel before E10 was introduced in 2021. If anything, it is the safer choice for your engine.

Will I notice a difference switching between E10 and E5?

Most drivers will not notice a difference in normal driving. If you have a car that benefits from higher octane (some turbocharged or performance engines), you may notice slightly smoother acceleration. The fuel economy difference of 1 to 2 percent is real but too small to feel day-to-day.

Can I mix E5 and E10 in the same tank?

Yes. E5 and E10 are fully miscible. You can top up with either grade at any time without any issue.

How often do these price inversions happen?

They occur daily across most regions. The CMA price transparency scheme means forecourts update prices regularly, and the variation between retailers is wide enough that E5 opportunities appear consistently. Check the comparison tool before your next fill-up to see what is available near you.

For the full breakdown of E10 vs E5 — including compatibility, ethanol content and environmental considerations — read our E10 vs E5 complete guide. For general fuel-saving strategies, see our 15 ways to save money on fuel.