Test driver

In motorsport it is common to have one or more test drivers who work with the mechanics to help develop the vehicle by testing new systems on the track.

In specific motorsports

Formula One

In Formula One, the term third driver is used to designate a test driver. Third drivers do not compete in Grands Prix, but are used by teams to help the race drivers and engineers with car development.

Third drivers can only be used in Friday practice sessions during a Formula One Grand Prix meeting, replacing one of the team's two race drivers.^[1] With in-season testing currently heavily restricted in Formula One, this can be an opportunity to give new or younger drivers a chance to test the car. Teams have also been known to use third drivers for publicity reasons, sometimes by fielding a local driver. However, as this opportunity comes at the expense of practice time and the chance to work on car set-up for one of the race drivers, its value to the team must be considered carefully.

In the

2005 Formula One season McLaren

ran third drivers and also had a successful season. Despite this, not all teams opted to take advantage of the third driver rule, with some teams saying that it was too expensive to run a third car on a Friday.

Starting with the

2007 season

, the regulations were changed to their current form so that while a team could run a third driver during Friday practice, they were no longer allowed to provide them with a dedicated third car. Subsequently, most teams choose not to run a third driver in order to give their race drivers maximum practice time.

Third drivers are still used occasionally, most notably

2010 season. Also, on several occasions, third drivers have acted as reserves, racing if one of the team's two race drivers is injured or otherwise unable to race, as in di Resta's case during the 2017 Hungarian Grand Prix,^[2] where he replaced Felipe Massa

, who became ill during free practice.