Diesel Set to Rise Again as Petrol Slips in Portugal

Motorists keeping an eye on the pumps have another mixed week ahead: the cost of topping up a diesel tank is set to edge higher, while unleaded drivers should finally see a modest reprieve. Even so, taxes still swallow more than half of every euro spent on fuel in Portugal, meaning the headline numbers rarely tell the whole story.

What drivers can expect next week

The Directorate-General for Energy and Geology (DGEG) is signalling that diesel will climb by about 2 cents per litre, placing the national average around 1.543 €/L. By contrast, petrol 95 is forecast to dip roughly 2 cents to 1.675 €/L. These movements assume that Lisbon keeps its temporary tax breaks on fuel in place, a policy that has softened price shocks since 2022 yet still leaves Portuguese households paying some of the costliest fuel in southern Europe.

Why diesel keeps climbing while petrol eases

Traders point to a cocktail of winter demand, tight refinery margins and higher shipping costs for middle-distillates to explain the latest uptick in diesel. Meanwhile, cooler headline crude prices—benchmark Brent is trading well below the peaks seen last summer—together with a stronger euro and lower carbon intensity penalties have nudged petrol lower. Add the volatile exchange rate, Portugal’s expanding biofuel mandate and the widening price spread between distillates, and the diverging paths of the two fuels become easier to understand.

Taxes still dominate the bill

Even after the Government’s ISP discount introduced at the height of the energy crunch, roughly 51 % tax share remains baked into every litre, according to ERSE. That is above the European average and dramatically higher than Spain’s 44 %. Each cent shaved off the factory gate price leaves the Treasury revenue side of the ledger untouched, and officials admit that a 2026 phase-out of the rebate is on the table. The current VAT claw-back mechanism also means that any rise in crude quickly re-inflates the pump price, complicating household budgets.

International oil market outlook hints at relief

Energy forecasters expect Brent to hover in a 60-70 $/barrel band through next year. The EIA and IEA both cite growing non-OPEC supply and muted demand as reasons the market may remain loose, although oversupply could be overturned by fresh geopolitical risk or deeper OPEC+ cuts. A projected 2026 slide toward the low 60s has prompted fleet operators to step up hedging activity, hoping to lock in savings before tax policy changes bite.

Portugal vs neighbours: the fiscal gap

Price boards just across the Guadiana highlight the disparity: Spain’s 1.39 €/L versus Portugal’s 1.54 €/L translates into a 15 cent gap that fuels so-called “border fuel tourism.” The Government argues that higher excise duties fund social programmes, but Parliament debates this autumn showed mounting pressure from regional economies and an increasingly vocal consumer lobby to narrow the divide.

Looking ahead: how long can discounts last?

All eyes now turn to November budget talks, where lawmakers will decide whether to keep the ISP rebate and the lower carbon levy. Finance ministry scenarios suggest diesel could jump to a 1.77 €/L scenario if tax relief is scrapped overnight. Officials favour a gradual rollback to avoid another spike in the cost-of-living, yet critics say the strategy postpones an inevitable reckoning with the green transition. Until then, motorists would be wise to consult predictive tools and choose fill-up times carefully—small moves at the wholesale level can still shave euros off a family’s monthly fuel bill, especially for long-distance motorists.