The Frenchman, who is embarking on his second season in Formula 1, says that the new car has given him a positive feeling, yet recalled that last year's Toro Rosso disappointed after a strong winter.
"My feeling is positive but if you look one year before we were saying the car was good, we were happy and look where we ended up," he said.
"The main focus we have is to understand the car. We have many options and many new things that we want to explore as much as possible.
"I'm confident that the car will be a step forward but it will probably take a bit of time to fully understand."
Toro Rosso is looking to improve on a difficult 2012 season where its only managed ninth in the constructors' championship.
Vergne hopes his own improvement as a driver will help the team.
"There are areas we need to work on, but once we understand everything the new car can do we will give ourselves a much better car," he said.
"I feel like I am a better driver, have much more experience and my understanding of the car is better than this time last year.
"Everything is much more automatic, and that's a nice feeling."