Sebastian Vettel has described the new front wing added on Formula 1 cars this season as "ugly" and has questioned why the wing has been made wider to encourage overtaking when it had previously been made smaller for the same reason.
The German and some of his colleagues remain unconvinced the aerodynamic regulations for 2019 will make overtaking any easier.
The biggest change for this year is the front wing, with the package of changes designed by the FIA and Liberty Media to promote wheel-to-wheel racing.
When asked about the wing, Sebastian Vettel said in Barcelona: "It's pretty ugly.
"It's too wide for me. I don't know why we've done that," said the Ferrari driver.
"A few years ago we made it smaller for overtaking, now it's been made wider for overtaking."
Another change for 2019 is the higher rear wings, and Renault's Nico Hulkenberg said on Monday that it feels like driving with "a parachute" attached.
He also said increased drag makes the cars slower in a straight line.
"This morning it seemed to me that the braking areas are much smaller," said Hulkenberg. "It is not going to be easy to put a nose in front, but we will have to wait for the races to see."
Yet another change this year is to the fuel regulations, with each driver given 5kg of extra fuel per race to stop the fuel-saving practice of so-called 'lift and coast'.
"The question is whether it is enough," Haas driver Kevin Magnussen told BT newspaper.
"I think a lot of the extra fuel will be eaten up by the increased drag of the new wings at the front and the rear. So it will surprise me if we can completely stop the coasting.
"I just hope it's not as bad as last year," the Dane added.