"When downshifting, Sebastian needs a stable rear for his special style of driving. With all the new systems, he doesn’t have that yet," Marko is quoted as saying by Germany’s Sport Bild.
"In 2012 it was the same and by the time he was happy with the rear he was unbeatable.
"We don’t understand why Vettel’s tyre wear was so much higher than Ricciardo’s [in China] but we’re investigating whether his chassis has a fault."
Marko added that the 26-year-old Vettel will be given a new ‘Suzie’ in order to determine whether the problem indeed lies with the chassis.
"When she’s ready, Vettel will get it," Marko added.
"2014 is so complex that even the engineers don’t understand everything.
"That makes it even harder for Seb to tune the car to his needs.
"But Sebastian is a perfectionist. He’ll tinker with it until he gets it right."