Diesel is more expensive than petrol again because its refining margins have surged since the start of the conflict in the Middle East, according to the Banque de France. From 5 to 11 October 2026, diesel sold for an average of €2.330/L against €2.124 for SP95-E10, a gap of 20.6 cents. Over the whole of 2026, the average gap stands at −12.1 c€/L (E10 minus diesel), whereas diesel was 6.6 c€ cheaper than E10 in 2025. This reversal is not a first: it had already happened in 2022.
Why diesel became more expensive: refining and reduced supply
According to the Banque de France blog post no. 464, published on 13 October 2026 with data up to 28 August, petroleum product prices rose by about 26% between February and August 2026. The rise in the average crack spread, meaning the gap between the forward price of the refined product and that of crude, contributed about 15 points to this increase, or nearly 60% of the cumulative change. In the Insee basket for 2026, road diesel has a weight of 49.3% and petrol 44.7%.
The diesel crack spread in North-West Europe averages about $50/barrel from April to June, then exceeds $70/barrel in July. The petrol crack spread is negative in April, then rises to $23 in May, $26 in June and $40 in July. The Banque de France therefore describes diesel as tight from March and petrol as clearly affected from June. Our records show the same sequence at the pump: an average gap of −25.2 c€ in April (diesel at €2.246/L against €1.994 for E10), a narrowing to −3.0 c€ in June, then a new widening from July.
The Banque de France gives three reasons for the tightness in diesel. The Strait of Hormuz has been closed since the conflict between the United States and Iran began on 28 February, sharply cutting exports of crude and refined products from the Gulf, on which many countries remain heavily dependent. Ukrainian attacks on Russian refineries and export infrastructure have limited deliveries of Russian diesel. Finally, “diesel demand is relatively insensitive to prices”, because it is tied to road freight, shipping and agriculture. For French refining capacity and diesel imports, see our article on refineries in France and our diesel imports.
According to the International Energy Agency, refineries processed about 810 million fewer barrels between March and August 2026 than a year earlier, an average of 4.4 million barrels per day and about 4% of world consumption. The Banque de France adds that these tensions can last several months after crude returns to normal, and that high crack spreads can limit the fall at the pump even if Brent declines.
How to read the gap between diesel and E10
In this analysis, the gap is calculated as the average price of E10 minus that of diesel, in euro cents per litre (c€/L). A positive gap means diesel is cheaper than E10, which is the case every year from 2009 to 2021 in our series. A negative gap means diesel is more expensive.
Our averages are calculated from the history of prices declared by stations and published on data.gouv.fr. The figures may therefore differ slightly from other price series. The years 2008 and 2013 are not in the annual series, and 2026 is calculated over the months elapsed. The full curves are on our page on the price gap between diesel and E10.
From a diesel advantage to the reversals of 2022 and 2026
From 2009 to 2021, diesel is cheaper than E10 every year in the series, with a gap between 4.6 c€ (2018) and about 20 c€ in 2009. The 2009 figure is only an approximate benchmark: E10 was only launched in spring 2009, which makes that first year hard to compare with the following ones.
In 2022, the situation reverses: diesel averages €1.870/L, against €1.762 for E10, a gap of −10.8 c€. The gap turns positive again in 2023 (+5.6 c€), then 2024 (+8.0 c€) and 2025 (+6.6 c€). In 2026, the reversal returns with diesel at €2.060/L against €1.939 for E10: −12.1 c€, the annual gap most unfavourable to diesel in our series.
| Year | Diesel (€/L) | E10 (€/L) | Gap (c€/L) |
|---|---|---|---|
| 2022 | 1.870 | 1.762 | −10.8 |
| 2023 | 1.813 | 1.869 | +5.6 |
| 2024 | 1.717 | 1.797 | +8.0 |
| 2025 | 1.648 | 1.714 | +6.6 |
| 2026 | 2.060 | 1.939 | −12.1 |
2026 month by month: a gap widening since the summer
From April 2026, diesel is clearly above E10: €2.246/L against €1.994, or −25.2 c€. The gap then narrows to −10.1 c€ in May, then to −3.0 c€ in June (€1.964 against €1.934), its lowest monthly level of the year.
It widens again to −8.9 c€ in July, −20.7 c€ in August and −20.4 c€ in September. In October, the current month, it reaches −21.2 c€ with diesel at €2.335/L and E10 at €2.123.
Week by week: only two weeks in diesel's favour
Over the last 24 weeks, the gap is positive only twice: from 22 to 28 June (+0.6 c€, with €1.891 for diesel and €1.897 for E10) and from 29 June to 5 July (+0.7 c€, with €1.889 and €1.896). The other 22 weeks show diesel more expensive than E10.
From the week of 6 to 12 July, the gap turns negative again (−1.8 c€) and widens quickly: −8.4 c€, −14.0 c€, −19.2 c€, then −20.6 c€ in early August. It peaks at −23.5 c€ from 21 to 27 September (€2.365 against €2.130), before easing back to −20.6 c€ from 5 to 11 October.
| Week | Diesel (€/L) | E10 (€/L) | Gap (c€/L) |
|---|---|---|---|
| 15 → 21 June | 1.932 | 1.919 | −1.3 |
| 22 → 28 June | 1.891 | 1.897 | +0.6 |
| 29 June → 5 July | 1.889 | 1.896 | +0.7 |
| 6 → 12 July | 1.943 | 1.925 | −1.8 |
| 14 → 20 September | 2.370 | 2.145 | −22.5 |
| 21 → 27 September | 2.365 | 2.130 | −23.5 |
| 5 → 11 October | 2.330 | 2.124 | −20.6 |
Diesel has risen more than E10
Between the week of 29 June to 5 July and that of 5 to 11 October, diesel goes from €1.889 to €2.330, a rise of 44.1 cents. Over the same period, E10 goes from €1.896 to €2.124, a rise of 22.8 cents. Diesel has therefore risen nearly twice as much as E10, by 21.3 cents more: this difference in increases takes the gap from +0.7 c€ to −20.6 c€. Its weekly peak over the period is €2.370/L, reached from 14 to 20 September.
For a driver, the difference shows directly at the pump: with a gap of 20.6 c€/L, a 50-litre tank of diesel costs about €10.30 more than a tank of E10 at the average price of the week of 5 to 11 October.
Taxation: a historical advantage that has narrowed
Historically, diesel enjoyed more favourable taxation than petrol, with a lower TICPE (formerly TIPP) fuel excise duty, to encourage the purchase of diesel vehicles. This advantage has narrowed with the gradual alignment of taxes. The details are in our article on the breakdown of the price of a litre of fuel.