Red Bull have won each of the five races so far this season and scored four one-two finishes.
Such was the RB19’s performance superiority in Miami, Aston Martin’s Fernando Alonso finished over 25 seconds behind Verstappen as he completed the podium in third place.
“Five races, five wins, plus the sprint, four one-two finishes. We’ve never, ever had a start like this,” a delighted Horner told Sky.
“We are wondering: ‘Where are the others?’
“We have made a normal step over the winter. Where did Ferrari and Mercedes go?
“They are working hard on big upgrades for Europe. With the penalty, we have to upgrade our car later in the year.
“It’s important for us to get as much fresh air as we can, between ourselves and the opposition.”
Despite their current dominance, Horner insisted Red Bull will feel the impact of their F1 cost cap punishment sooner rather than later.
“You’ll see from the next race that big upgrades are coming,” Horner said.
“We have to be super selective in what we test and what we develop.
“The car got off to a great start so we aren’t having to solve big issues, big problems. We are able to focus on incremental gains.
“I do expect it to converge later in the year.”