Mercedes boss Toto Wolff says he would be “surprised” and “disappointed” if the FIA’s imminent ruling on engine upgrade opportunities influences its fight with Ferrari at the front of Formula 1.

A decision is looming from motor racing’s governing body about which manufacturers it judges as being behind enough to be granted Additional Design and Upgrade Opportunities (ADUO).

Scope for an in-season engine upgrade could be critical in the fight at the front of the grid, with Ferrari openly expecting it will fall into the group that will be allowed one.

But Wolff suggested, based on his own team's analysis of the internal combustion engine element that is being looked at, there is not much real difference between those at the front of the field.

He thinks it is only Honda that potentially looks to be in enough trouble that it needs some extra assistance.

This is why Wolff said he will not be satisfied if the FIA gives Mercedes' closest rivals a green light for engine improvements.

“It seems for me there’s one engine manufacturer that has a problem, and we need to help,” he said. “But then all the others are pretty much in the same ballpark.

“So I would be very surprised actually to see, and disappointed, if ADUO decisions come up with any interferences into the competitive pecking order as it stands at the moment.”

Wolff’s argument is based on his belief that the new upgrade system was never meant to be a mechanism to help those who had not made the best engine to come out on top.

“The principle of the ADUO was to allow teams that were on the back foot to catch up - but not to leapfrog,” said Wolff, when asked by The Race about his thoughts on the process.

“It needs to be very clear that whatever decisions are being made and whatever team is granted an ADUO, any decision may have a big impact on the championship if not done with absolute precision and clarity and transparency.”

Ferrari playing catch-up

Ferrari has not shied away from the fact that it sees the upgrades system as a chance to slash the advantage that Mercedes has enjoyed in the early part of 2026.

Team principal Fred Vasseur said at the Chinese Grand Prix: “The addition of the ADUO will be an opportunity for us to close the gap.”

With Vasseur suggesting that its power deficit against Mercedes is as much as 0.8 seconds right now, any help on this front would certainly be a welcome boost.

For with Ferrari also working on a raft of aerodynamic changes for its SF-26, extra help on the power front could help ignite a full-on title challenge against Mercedes.

But some of Ferrari’s rivals have questioned whether its engine should be judged as being behind at all.

They argue that some strategic choices that Ferrari has made with its design - including a small turbo and its exhaust wing - have a direct impact in lowering its power potential, so need to be taken into account.

Amid suspicions of gamesmanship among manufacturers perhaps hiding their full potential so they be granted upgrades, intrigue in the development process has shot up in recent weeks.

Wolff was clear that the FIA needs to be robust in its measurements and how it deals with things to avoid a scenario where it grants upgrades to a manufacturer that is not really behind.

“It needs to be clear that gamesmanship hasn’t got any place here, but it needs to be with the right spirit here that the FIA acts upon an ADUO,” he said.

Rules process

The FIA is due to make a call after the Miami Grand Prix on where it thinks each power unit stacks up.

That outcome of that will then decide which of the manufacturers will be allowed extra development and upgrade opportunities both for this season and 2027.

The rules allow those manufacturers that are 2% adrift of the benchmark power unit the chance for one upgrade this season and another next year.

Anyone that is judged to be 4% adrift or more will get two changes this season and another two for 2027.

The manufacturer that is judged to be ahead will be unable to work on any upgrades, which could then put them on the back foot if others are able to catch up.

Wolff said Mercedes was not fearful about how things could play out but was carefully "monitoring" the situation.

“I wouldn’t call it 'worried',” he said. “I think we are all monitoring how decisions are being made.

“We have precise data from our own analytics of where we see engine performance of our competitors and ourselves.

“I think the FIA is looking at the same data and, certainly, I would very much hope, they continue to see themselves as protecting the integrity of the sport.

“You don’t want to allow an ADUO to a team that suddenly leapfrogs someone. The ADUO was always meant as a catch-up mechanism and not as a leapfrog mechanism.”