This year, Russian 20-year-old Daniil Kvyat has impressed despite stepping straight into F1 as the reigning GP3 champion.
Only a few months younger than Kvyat is Carlos Sainz jr, whose father and namesake is the well-known two-time world rally champion.
Son Sainz, 19, has concentrated on single seaters, and so far in 2014 his F1 aspirations are on track as he is leading the highly-rated Formula Renault 3.5 series.
He is undoubtedly the next in line for a Red Bull-powered future in F1.
"He is on the right track," confirmed Toro Rosso team boss Franz Tost, referring to Sainz's winning season so far in 2014.
"The season has just started and there are a couple of good drivers in the world series and we want to see how they develop during the season.
"But Carlos is doing a good job," Tost told Spain's El Confidencial. "If it continues I am sure he will sit in a Toro Rosso in a test or on a Friday.
"It really depends on the driver," he continued. "He is the one who steps on the gas. I always tell the drivers 'It is you who decides your future, not us'.
"Last year at this point I was sure Antonio Felix da Costa would be driving for us -- I would not have bet that (Daniil) Kvyat would be instead."
Tost also hailed Daniel Ricciardo's progress in 2014 after stepping up from Toro Rosso.
But, unlike Red Bull figures Christian Horner, Dietrich Mateschitz and Helmut Marko, the Austrian said he has not been "surprised" by Ricciardo's pace at Red Bull.
"I expected him to be very competitive and comfortable in a very short space of time," said Tost, "so it has not been a surprise to me.
"Ricciardo gives very clear and detailed technical feedback, and so maybe he has just adapted to the circumstances more quickly than Vettel" he added.
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