Glossary of Motorsport Terms

• Impact wrench - A tool specifically designed for rapidly winding off and on wheel nuts, allowing the changing of wheels and tyres to be performed faster during pit stops. Also known as an impactor, air wrench, air gun, rattle gun, torque gun.
• Impound Rule - NASCAR's version of Parc Fermè, used at certain tracks
• In-lap - Any lap which concludes with a visit to the pits,[citation needed] especially a pre-arranged pit stop, either during a race or during practice or qualifying. Oftentimes drivers push hard to drive fast on their in-lap (despite perhaps having worn out tires) in order to gain time during the pit stop sequence.
• Incident officer (often IO or I/O) - A motorsport marshal who is in charge of other marshals on the track, allocating duties to them. Second in terms of ranking to observer. In hillclimbing, they are responsible of the radio communication.
• Independent - A competitor (team or driver) taking part with no or very little backing from a manufacturer. They have their own championship within the World Touring Car Championship, where there is a strong manufacturer presence.
• Installation lap - A lap done on arrival at a circuit, where drivers can test their car functions, such as throttle, brakes and steering before heading back to the pits, without crossing the finish line.
• Intermediate - A wet weather tyre of lighter grooving than a wet weather tyre. Sometimes an intermediate is a slick tyre with grooves cut into it. It is used for conditions between dry and wet conditions, most often when the track is wet but it is not actually raining.
• Invert - The portion of the field which is started by reverse qualifying speed. With an invert of five, the fifth-fastest qualifier starts first and the fastest qualifier starts fifth. The rest of the field starts by their qualifying speed (sixth fastest starts sixth). The invert is often not announced before qualifying or a dice/die roll happens after qualifying.