Formula 1’s one-off return to Malaysia’s Sepang circuit in 2026 will test how the current cars manage heat, tyre wear, electrical energy and rain. Sepang is stepping in as a proxy host for the Bahrain Grand Prix, bringing back a track whose hot, humid climate and regular late-afternoon downpours are familiar to some in the sport but new to most of the drivers on the grid.

The cars have changed substantially since the circuit last hosted a race, leaving teams with many unknowns. The ambient heat and humidity, along with the abrasive track surface, are among the few characteristics they already understand. The surface has been compared by at least one driver to sandpaper, and its open texture was chosen to withstand harsh weather and drain water quickly.

That texture is expected to put tyre life under pressure. Formula 1 tyres generate grip through hysteresis, in which the viscoelastic rubber does not immediately return to its original shape after being compressed against the track. As the tyre rotates, some kinetic energy becomes heat while the rubber recovers, and a rougher surface raises temperatures further.

That makes tyre degradation likely to play a larger role than it has at several other races this season. The prospect offers a change after the Azerbaijan Grand Prix, where the soft tyre still made a one-stop strategy an almost certain choice. Pirelli has selected compounds toward the harder end of its range for Sepang, but not its hardest: the available tyres are the C2, C3 and C4, one step harder than the selection in Baku.

Sepang’s combination of long straights and sharp corners could make energy harvesting and deployment relatively predictable for teams. The pattern may resemble China, where drivers experienced the so-called “yo-yo racing” that both fans and drivers dislike. However, the tyres’ response to the circuit could change how closely cars can follow and how often they can attack.

Fernando Alonso, who took his first Formula 1 pole position at Sepang in 2003, said the circuit’s middle sector would be difficult to use for overtaking because drivers would need to preserve battery charge for the straights. “We come to an incredible circuit now,” he said. “It's going to be sad, the middle sector, because we cannot use the battery there - if not, you don't have [sufficient charge] for the three consecutive straights, you know, from Turn 14 to the last corner, then last corner to Turn 1, Turn 2 to Turn 4, you have to use the full 100% battery on those three straights, so the rest is just charging the battery.”

The result could be slower running through the middle sector, while drivers who use electrical boost to pass may lose ground later in the lap. The current cars send substantial energy through the rear tyres when the electric motor is deployed. Engineers will need to consider the immediate risk of surface temperatures spiking as well as longer-term thermal degradation.

George Russell said overheating could make Sepang different from other circuits associated with energy-related changes in pace. “I think the big difference on this circuit compared with other so-called yo-yo circuits is the tyre overheating,” he said. “So circuits such as Melbourne, Silverstone, Monza, there wasn't actually that much tyre overheating from the surface. Canada as well. So that kind of allowed the drivers to stay a little bit closer within that one second [which grants access to additional power through overtaking mode].”

He said Baku was also cool enough for drivers to remain close, but expected surface overheating to be a significant concern in Malaysia. “Even in Baku it was quite cool, the drivers could stay close. Whereas here, surface overheating is going to be a huge thing. You'll be overheating the tyres even on the outlap of a qualifying session, which may make it more challenging to follow closer and to re-attack once you've been overtaken. But that's a total unknown currently.”

After several races with little or no degradation, Sepang could produce a wider range of strategies. In that respect, it may have something in common with the circuit that usually stages the Bahrain Grand Prix, which also has a rough surface that wears tyres quickly.

Rain adds another set of uncertainties. Malaysia often sees a torrential downpour at about 4 p.m., though it can arrive earlier or clear quickly. The heat can dry the track rapidly, leaving conditions too damp for dry tyres but not wet enough for intermediates.

The new wet-weather tyres have had limited running this year, and there are concerns that the intermediate may be too hard to warm up quickly. Carlos Sainz said a wet race would test the tyres and the regulations, as well as the power unit’s behaviour in slippery conditions. “It will be a good test for sure if it rains,” he said. “A good test for the regulations also because I think with all the issues we have with downshifts, with harvesting, power, variability, corner to corner, the wet is going to be a challenge for sure.”

Sainz added: “Both from a tyre standpoint - from what I heard from people that have run them, this year's wet tyre and inter-tyre are difficult - plus the power unit factor [ie large delivery of torque in slippery conditions], it will be for sure a good test.”

Isack Hadjar said his experience of testing the wet tyres in Japan left him concerned about grip. “The only thing I remember from Japan [where he tested the wet tyres] is that the tyres have zero grip,” he said. He would welcome a wet qualifying session, but said the combination of rain and energy management could make a race chaotic. “It would make the racing very dangerous with a lot of water. So, I would definitely welcome any competitive session to be a rain session and qualifying. But at the moment, for the race, with all this energy, I think it would create a bit of chaos. I don't think we're much ready for that. But definitely qualifying - why not?”

Sepang’s history also reflects the expansion of Formula 1 into Asia. The circuit became a major marker of the sport’s eastward growth under Bernie Ecclestone, with large facilities and prominent architecture funded by governments seeking to raise their countries’ profiles. It also helped establish the design approach associated with architect Hermann Tilke, who favoured wide tracks with long straights leading into sharp corners, intended to encourage overtaking by creating opportunities for driver mistakes.

Critics of Tilke’s style have argued that such circuits are bland and do not deliver the promised passing. In Malaysia, the state-backed venue also faced a commercial challenge: ticket prices were beyond what most local fans could afford, with a single ticket costing the average person a month’s wages. Grandstands were therefore often largely empty, an outcome that did not provide the country with the image it wanted to project.

Malaysia ended its hosting agreement in 2017, one season before it was due to expire, after 18 years on the Formula 1 calendar. Sepang’s 2026 appearance is a one-off, and the circuit is expected to draw more fans this year than it did in the past. The race is scheduled for 3 p.m. local time, the same start time used in 2009 to accommodate European television audiences.

That 2009 race is remembered as one of the few in Formula 1 history to be stopped by a red flag and not restarted before the full distance was completed. Heavy rain arrived after the start, and when conditions did not improve, officials abandoned the restart. The timing of that start made a downpour likely, and the same afternoon scheduling this year raises a familiar prospect for a race in a region where rain and heat can quickly alter track conditions.

The 2009 event also showed that a switch to wet tyres may not solve every problem. For at least 10 laps before the rain became extremely heavy, drivers who had changed early to wet tyres suffered from overheating. With little running on Pirelli’s wet-weather rubber this season, whether the current tyres behave similarly remains unknown.

Based on reporting by Autosport.