1. Tax first, then the market: what actually makes the gap
In most of Europe the tax system favours diesel. Germany charges 47.04 cents of energy tax per litre of diesel against 65.45 cents on petrol, a difference of 18.4 cents net or about 22 cents with VAT (Energy Tax Act). When diesel nevertheless costs 20.5 cents more at the pump, as in late October 2026 (ADAC, 28 October), the market price of diesel sits roughly 42 cents gross or about 36 cents net above petrol. The gap is not made at the forecourt or by the tax office; it is made between the refinery and the depot.
It has not always been like this. In normal years German diesel costs less than petrol because of the tax advantage; the last time it cost more was autumn 2022, when Russian diesel exports disappeared. In the United States there is no tax preference for diesel, which is one reason the American gap is the widest of the four countries. Germany's fuel tax cut, in force since 1 October, does not change the gap, because it lowers both fuels by the same amount (see Germany's fuel tax cut).
2. The three reasons
First, the refining margin. A refinery turns a barrel of crude into a fixed bundle of petrol, diesel, jet fuel and residual oil, and the shares can only be shifted within narrow limits. When diesel is scarce, its price rises above petrol without any more diesel being made. In New York Harbor, ultra-low sulphur diesel averaged $111.27 a barrel above WTI crude in the week to 23 October 2026, while petrol was only $15.68 above it (our calculation from EIA spot prices). That gap, the diesel crack spread, came to about 53 euro cents a litre on 27 October before tax and distribution; the September monthly average of $110.84 was the highest since the series began in 2006.
Second, supply. Russia, Europe's largest diesel supplier before 2022, had extended its diesel export ban to 31 October after drone strikes forced three of its six largest diesel refineries to cut or halt output in September (Hydrocarbon Processing, 16 September); according to Reuters the ban is to run to the end of the year, with deliveries to the US handled through exemption quotas (29 October). The Gulf states export finished products, and those shipments are recovering more slowly than crude: in October 3.1 million barrels a day of products left the Gulf according to Vortexa, just over half the pre-war level (Reuters, 3 November). Petrol is less affected: the United States, the biggest petrol market, makes its own, and US gasoline stocks of 209.2 million barrels in the week to 23 October were far more comfortable than distillate stocks of 102.8 million (EIA, 28 October).
Third, demand. Diesel moves trucks, ships, farm machinery and construction sites and is chemically the same as heating oil; in autumn the heating season comes on top. Petrol peaks in summer and fades in autumn. That the gap keeps widening in autumn is partly a matter of the calendar.
3. Four countries, one pattern
| Country | Diesel | Petrol | Gap | Date, source |
|---|---|---|---|---|
| United States | $6.352/gal | $4.269/gal (regular) | +$2.08 (+49%) | week of 26 Oct 2026, EIA |
| Germany | €2.289/L | €2.084/L (E10) | +20.5 ct | 28 Oct 2026, ADAC |
| France | €2.337/L | €2.096/L (E10) | +24.1 ct | 1 Nov 2026, prix-carburant.eu |
| Spain (last day of the diesel advantage) | €1.938/L | €1.952/L (95) | −1.4 ct | 30 Sep 2026, El Independiente (ministry data) |
| Spain (week of 26 Oct) | €1.888/L | €1.751/L (95) | +13.7 ct | EU Weekly Oil Bulletin, week of 26 Oct 2026 (via fuel-prices.eu) |
Spain shows how much policy distorts the picture: in September diesel was still cheaper than petrol at Spanish pumps, because the state took 20 cents off diesel but only 5 off petrol (El Español). Since 1 October both fuels get the same relief: 20 cents in October and, because September's year-on-year rise (diesel +34.0%, petrol +27.5%) tripped the safeguard clause, 20 cents in November as well; December will be 13 or 20 cents depending on whether INE's October figure again clears the 15% threshold (Royal Decree-Law 25/2026, BOE of 30 September). The diesel advantage is gone: in the EU Weekly Oil Bulletin for the week of 26 October, Spanish diesel cost €1.888 and petrol 95 €1.751, a gap of 13.7 cents. France has been releasing 10 million barrels of diesel from strategic stocks since 28 October and holds out up to 18 cents a litre less; on 1 November average prices fell at 22 of 30 brands (prix-carburant.eu). The UK picture is on UK petrol and diesel prices forecast.
4. When does the gap close again?
The EIA expects a US gap of $1.66 a gallon in the fourth quarter of 2026 (diesel $5.81, petrol $4.15) and $0.93 in 2027 ($4.49 against $3.56), smaller but still unusually wide (STEO, 6 October 2026; the next edition is due on 10 November). The condition is that most Gulf production returns by the end of the second quarter of 2027 and that distillate stocks rebuild; the International Energy Agency expects the gasoil market to stay tight well into 2027 (Oil Market Report, 14 October).
Europe has no comparable official forecast. Three things would close the gap faster: Russian refineries return and the export ban falls; Gulf product shipments normalise after a reopening of the strait (see Hormuz reopening: three scenarios); and winter ends. Until then, anyone choosing between a diesel and a petrol car should budget with today's gap, not 2019's. More on the shortage itself on Diesel shortage winter 2026/27.
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