The purpose of "downshifting", or shifting the transmission down from a higher gear to a lower gear, is so that a driver can accelerate their car as fast as possible when exiting a corner that they had to slow down for. Heel-toe downshifting saves time on the track because, if it is not used, time will be lost gaining control of an unstable car or shifting into the correct gear before the gas is applied. The time taken to shift into gear just before accelerating out of the corner can cost valuable time, so shifting down while braking kills two birds with one stone. The reason the "heel-toe" technique is required in this process is so that the driver is able to match the RPM (revolutions per minute of the engine) of the next gear down by hitting the throttle (gas pedal) with their heel (known as "blipping" the throttle) and braking with their toe.
This technique, that will be explained in the following steps, will allow smooth and quick downshifts while braking for a corner. The whole process will take about 1-2 seconds per gear change, depending on the car and driver. The necessary steps are broken into small windows of time, and should be practiced individually without driving while first learning. The skill level of this task is a beginner to advanced driving technique and the driver should first know the basic techniques to driving a road course (i.e. driving line, braking technique, how to drive a manual transmission, etc.).
Warning: Race car driving is a dangerous sport and can result in serious injury or death if proper safety gear is not implemented. The technique shown in this instructable is purely meant for use on an off-highway racing facility. Obey all traffic laws and do not try this on the street. I am not responsible for any actions taken by those who read and use this instructable.
Necessary Equipment: Manual transmission car that is safe enough for track use, as well as proper driving safety gear.
*Note: The car used in this instructable is a 1995 Mazda Miata with a 5-speed manual transmission. The steps outlined are a process of downshifting from 4th gear to 3rd gear in this car, but the steps apply to any gear your car is currently in when you follow this instructable.