Mercedes believes rear tyre degradation on race day is a main weakness of Red Bull's RB16B compared to the reigning world champion's more "neutral" W11.
Max Verstappen has showcased in qualifying the single-lap pace of Red Bull's 2021 charger and the Dutchman has also led the most laps this season. However, he has lost out to Mercedes and Lewis Hamilton in three out of the four races held so far this year although there was little to choose between the two drivers at times.
Mercedes trackside engineering director Andrew Shovlin believes Red Bull's relative weakness in race trim is rooted in the RB16B's rear tyre degradation; an observation substantiated by how last Sunday's Spanish GP unfolded in favour of the Brackley squad.
But while Mercedes currently holds an edge over its Red Bull rival in the tyre department, Shovlin insists it's a tenuous advantage and one the German outfit may not enjoy at every venue.
"We are still not really at a stage where we go in thinking we’ve got a better race car or we are better at looking after the tyres," explained the Mercedes engineer.
"It is actually quite hard to say what it was [in the Spanish GP]. We were able to sit behind them and, when you are the lead car and someone can sit on your gearbox for a whole stint, it is not normally good news.
"But we are still in the stage of the year where we are collecting data across the different tracks. But it does look to be a bit of a trend that maybe we have got a slightly more neutral car.
"Theirs seems to be a bit harder on the rear tyres over a stint whereas we are using both axles quite well. But we will see with some more data whether that is really a feature of the car or just how we are setting it up."
Red Bull team boss Christian Horner agreed with Shovlin's view but insisted the spread is still very tight between the two rivals.
"I think the Mercedes - and we've seen it since Bahrain - their race pace has been better than ours at each GP that we've seen so far," he said. "I think that their degradation has been better than ours.
"So we knew these last two circuits would play to their strengths. They have done that.
"But we're an awful lot closer than we have been and I think if we can find some more race pace it's still very, very tight between the two cars."