Sebastian Vettel says Ferrari's downforce and cornering gains have come to the detriment of the SF1000's speed on the straights.
Last year, cornering speed was a specific weakness of the Scuderia's SF90 while the car was as fast as a bullet down the straights.
Ferrari's engineers subsequently worked hard to improve the downforce qualities of its 2020 contender. But the improvements have led to a trade-off which has hurt the top speed of the SF1000 which Vettel now feels is "draggy".
"We can feel the car is better, I think Sector 3 feels better," Vettel said, echoing comments made yesterday by teammate Charles Leclerc.
"We also know that it does come with a trade. We still have some work to do, we are slower than we want down the straights because we are a bit draggy.
"We are aware of that, but the objective was to put more downforce on the car which I think we did.
"Sector 3 does feel better, but obviously getting out of Sector 3 and down to Turn 1 doesn’t feel as good as last year.
"Certainly in the corners is where you feel the difference, and where we improved, but it looks like others are even a bit faster. That’s where we are I guess. There’s a lot of work to do."
©Ferrari
Overall, Vettel believes that Ferrari's new car represents a step forward relative to last year's charger.
The German hopes some fine-tuning will dial out some excess aerodynamic drag although he insists the current configuration will prove beneficial on race day.
"We worked very hard over winter, and I think our car is a step forward," he added. "Currently it does come with some more drag, but I think we are aware.
"We are pushing as hard as we can to get rid of the drag and make it more efficient. But we also believe that come race day, it gives us an advantage the way it is set up now, so we will see.
"I think it will be key to obviously develop the car, especially since it seems that we’re not the very fastest right now."
Charles Leclerc will take over from Vettel for Friday's final pre-season session.
Gallery: The beautiful wives and girlfriends of F1 drivers
Keep up to date with all the F1 news via Facebook and Twitter
