McLaren has added its concerns to the complex 'token' system that will govern car upgrades for 2021.

To cut costs amid the corona crisis, the teams will only be allowed to make minor modifications to limited areas of their 2020 cars for next season.

But we reported recently that Racing Point and Alpha Tauri have found a loophole, as their agreements to buy parts from Mercedes and Red Bull respectively permit upgrades without having to trade in the 'tokens'.

"That I believe would be unfair, because we've got only two tokens and everybody should be limited to that," said Ferrari team boss Mattia Binotto.

Renault said it also has concerns about the "flaws" in the system.

McLaren, meanwhile, will have to use up all of its tokens simply to switch as planned from Renault to Mercedes power for 2021.

"We don't like it that customer teams get this free ticket to upgrade the gearbox and the suspension from 2019 to 2020 specification without having to use tokens," team boss Andreas Seidl is quoted by Auto Motor und Sport.

"From the beginning we have pointed out to the FIA that this could be a problem. We were promised that it would all take place in a manageable way," he said.

Seidl continued: "Only now as we define the details is it becoming clear what loophole is opening up.

"In comparison with our situation, this is not fair as our engine change was contractually agreed before the crisis.

"We are discussing it with the FIA now," he said.