The heel-and-toe gearchange is an advanced driving technique
which allows for smoother driving and braking. And smoother
braking means you can brake harder and faster which ultimately
results in faster lap times. Heel-and-toeing is done so
that consistent pressure can be applied to the brake pedal
Heel-and-toeing is done by keeping the top of your foot
on the brake during a downshift and blipping the accelerator
with the right side of the foot to bring up the engine rpms
as the downshift is made.
A good way to practice a heel-and-toe gearchange is to blip
the throttle during a downshift to match the revs of the
new gear without braking. Slowly, and as your skills improve,
introduce braking into the mix.