One of Red Bull's major advantages in Formula 1 this year is becoming clear - DRS.

Mercedes' Lewis Hamilton said the way Max Verstappen passed him in Saudi Arabia last weekend astonished him.

"I don't know how or why, but he passed me with impressive speed," he said.

"I didn't even bother to defend because there was a huge difference."

Red Bull's Honda-Red Bull Powertrains-powered car is impressive in a straight line, but it is believed the efficiency of the drag reduction system (DRS) overtaking aid is particularly strong compared to the competition.

"Lewis is right," Sky UK reporter Ted Kravitz said. "He says he's never seen anyone gain that much speed with DRS and does not understand how it's possible."

Indeed, other teams - like Ferrari - are actually struggling more than before in a straight line this season so far.

"In the dirty air it's a little worse compared to last year," Ferrari driver Carlos Sainz said.

"Perhaps it's due to the increase in downforce and the new regulations, but now the car is behaving in much the same way as the previous generation cars. It has become more difficult to follow an opponent closely."

McLaren's Lando Norris agrees: "In the dirty air, we have big problems following the other cars."