Toro Rosso have targeted fifth in the 2015 constructors' championship at the unveiling of their new car on Saturday.
"Our objective is to finish fifth and we are ready to do our best to achieve it," team principal Franz Tost said.
The STR10 was unveiled in Jerez on the eve of the first pre-season test.
"The 2015 season is a new challenge for all of us," added Tost. "We've put a lot of work into the STR10 and we are convinced that we will have a successful year,"
Toro Rosso scored 30 points last year with Frenchman Jean-Eric Vergne and Russian Daniil Kvyat - since promoted to sister team Red Bull - their drivers.
That total was 151 points down on fifth-placed McLaren - and 125 adrift of Force India in sixth.
The youngest driver line-up in F1 history has been entrusted with bridging that considerable gap.
Spaniard Sainz, 20, whose namesake father was the world rally champion in 1990 and 1992, will be first behind the wheel of the Renault-powered car on Sunday.
Seventeen-year-old Verstappen, the son of former F1 driver Jos, will become the sport's youngest ever race driver when he takes the start in Melbourne on 15 March.
"I can't wait for the season to start and tomorrow will seem like a very long day, watching Carlos in the car," said Verstappen, who will get his first taste of the STR10 on Monday.