Mercedes has a three-tenth advantage over Red Bull-Honda heading into Australia, according to an analysis done by a number of F1 engineers.
Germany's specialist Auto Motor und Sport claims Ferrari comes in next in third place, about 5 to 6 tenths off the pace.
Referring to Mercedes, Sebastian Vettel said: "They do fast laps with ease."
The publication said its analysis of the Barcelona testing pace involved multiple engineers who analysed laptimes, GPS data, tyre types used, and fuel load and engine mode estimates.
Mattia Binotto denied that Ferrari has been sandbagging. "What you saw is our potential," said the team boss.
After Ferrari comes Racing Point, then McLaren, Renault, Alpha Tauri, Haas and Alfa Romeo. Williams continues to bring up the rear, but is now as little as a tenth off the next best team.
Racing Point's technical boss Andy Green takes issue with the pecking order, though, claiming that the second Red Bull team Alpha Tauri is faster than it appears.
"You would expect that from a copy of the old Red Bull," he said, following accusations that Racing Point's own 2020 car is a 'pink Mercedes'.
McLaren driver Carlos Sainz agrees with that analysis.
"I currently rate Racing Point and Alpha Tauri most strongly," he said, referring to the battle for the top of the midfield.
"Racing Point's laptimes are puzzling as they started at a high level but didn't improve as much as the others," added Sainz. "I think they just don't want us to know how fast they are.
"I think if we want to defend our fourth place, they are our main rivals."
Haas boss Gunther Steiner, meanwhile, agrees with the Auto Motor und Sport-published hierarchy that claims the American team's 2020 car is faster than Alfa Romeo's.
"With harder tyres and more fuel in the tank, we were four tenths faster than them," he said.