LONDON (AP) -- Scott Speed, the only American driver in Formula One, was dropped by the Toro Rosso team Tuesday and replaced by Germany's Sebastian Vettel.

Speed and fellow Toro Rosso driver Vitantonio Liuzzi are among seven drivers without a single point after the first 10 of this season's 17 races. The 24-year-old Speed, from Manteca, California, has failed to score a point by finishing in the top eight of any race in his two seasons in F1.

F1 has proved a tough challenge for American drivers in recent times.

Since 1978, when Mario Andretti joined Phil Hill as the only American F1 champions, only a handful of drivers from the U.S. have found a seat in Formula One.

Eddie Cheever and Danny Sullivan never had any real success in F1 before going back to the States and finding fame and fortune. Michael Andretti, Mario's son, was already a star in the U.S.-based CART Series -- now Champ Car -- before he tried F1 in 1993.

Toro Rosso, a small budget F1 team, said the 20-year-old Vettel would replace Speed for the remainder of the season. Vettel has been a reserve and test driver with BMW Sauber, which agreed to release him for the move up to full-time F1 driver.

Vettel stepped in for BMW-Sauber's Robert Kubica at the U.S. Grand Prix and finished eighth, becoming the youngest driver to score a point in his debut.

"However, the current testing rules mean that he barely gets a chance to drive for us," BMW motorsport director Mario Theissen said. "Now he has been offered the opportunity to get inside a Toro Rosso cockpit. We have sponsored and coached Sebastian over a number of years. To place obstacles in his career path now would go against our concept of talent promotion."

Timo Glock, a BMW-Sauber test driver, will replace Vettel as the team's reserve driver.