Why Portugal Faces Cheaper Petrol Yet Costlier Diesel This Monday

The price boards outside Portugal’s filling stations are about to send motorists mixed signals. From Monday, unleaded 95 is forecast to edge down, while road-diesel inches up — a minor divergence that nonetheless reveals a great deal about the forces shaping the country’s fuel bill.

A curious Monday split at the pumps

Industry trackers consulted by the Automóvel Club de Portugal (ACP) tell us that the average cost of regular diesel could rise to roughly €1.567 per litre, an increase of about half a cent, whereas 95-octane petrol may slip to €1.703, or one cent less than last week. Those changes look trivial on paper, yet they matter to the 4 M vehicles that rely on petrol and the 3 M that run on diesel across mainland Portugal.

Why petrol and diesel are heading in opposite directions

Several market frictions are pushing the two fuels apart. The clearest is the recent rally in Brent crude, which closed at $69.42 a barrel on Thursday, its third straight gain. Diesel is more directly tied to crude’s spot movements, while petrol’s price still enjoys a small buffer from summer refinery margins that are finally easing. Meanwhile, a stronger US dollar is making imported fuel more expensive in euro terms, but the impact is being felt unevenly: refiners have hedged part of their petrol exposure, yet diesel purchases roll over week by week. Add in the traditional autumn lull in leisure travel — fewer petrol-powered journeys — and the price fork starts to make sense.

How global markets convert into Portuguese pump prices

Shifts on the trading screens are only one layer of the equation. Roughly 55 % of what you pay at the nozzle is tax: the Imposto sobre Produtos Petrolíferos (ISP), VAT and a carbon component. Earlier this year the government tweaked that mix — ISP went up, the carbon levy came down — with a pledge of overall neutrality for households. So far, that promise has held. The Entidade Nacional para o Setor Energético (ENSE) estimates that without those offsets the current Monday adjustment would have been twice as steep.

Looking beyond the first week of October

Analysts are already warning that the respite for petrol could be brief. Preliminary projections for 6-12 October signal a 2-cent jump in unleaded 95 and a 1.5-cent rise in diesel, assuming the extraordinary ISP rebates remain in place. Brussels, however, continues to press Lisbon to phase out those rebates by year-end. Should the Finance Ministry comply, ENSE models suggest pump prices could leap by up to 10 % during the fourth quarter, even if Brent stabilises.

What drivers can do now

Every céntimo still counts. Comparison apps such as Mais Gasolina show spreads of 12 cents a litre between the cheapest cooperative station and the priciest motorway stop within the same district. A 50-litre petrol tank filled at the low end of that range saves about €6 — enough to offset several weeks of the modest rise–fall cycle now in play. For diesel motorists clocking long commutes, loyalty programmes offered by the major chains continue to shave 5 % off the bill, often beating the headline change in wholesale prices.

Petrol down, diesel up — but only for now. The direction of travel after October will depend less on next Monday’s figures than on tax policy, carbon pricing and the euro–dollar duel. For Portuguese households already juggling higher electricity and mortgage costs, the fuel question remains one more line item demanding close attention.