Heel-toe downshifting and left-foot braking.

What heel-and-toe is

According to Wikipedia, heel-and-toe is a technique for cars with a manual gearbox: the right foot works the brake and the throttle at the same time while the left foot works the clutch. That lets the driver brake and downshift together, using a quick blip of the throttle so the lower gear engages smoothly.

The name is older than the method most drivers use now. Wikipedia explains that pre-war cars often had the accelerator in the middle, so the heel worked the brake and the toe the throttle. In modern cars the toe or ball of the foot stays on the brake and the side of the foot rolls onto the throttle.

Why match the revs

Driver61 describes the goal as matching engine speed to wheel speed, so the driven axle does not lock and the car stays balanced while braking into a corner. Its example: a 5th-to-4th downshift at 80 mph with the engine at 8,000 rpm needs about 10,000 rpm in the lower gear.

HP Academy explains what happens without a rev match. When the clutch comes up, the engine is forced to spin up suddenly, which can briefly lock or slow the driven wheels. The result can be anything from a car that feels unsettled to oversteer under braking, and HP Academy says the effect is worse in the wet. The link between braking, load and grip is covered on weight transfer.

The principles schools teach

HP Academy's points, in its own framing:

• Foot position. The most common method is braking with the ball of the right foot and rolling the outside of the foot onto the throttle. Pedal layouts differ, so other methods may be needed, and HP Academy says comfort and consistency matter most.
• Clutch timing. Release the clutch as the blip reaches its peak. Too big a blip leaves the revs too high; too small and they jump up when the clutch engages.
• Steady brake pressure. Keep brake pressure as constant as possible during the blip. A slight dip is normal even for professionals, and small dips usually only show up in data.
• Pedal setup. If the pedals are adjustable, set the brake level with or slightly below the throttle under hard track braking. A brake that sits much lower can make the driver lose pressure while reaching for the throttle.

Brian Beckman, in the "Why Smoothness?" part of The Physics of Racing, argues that most inputs should be gradual, and names the rev-matching blip on a downshift as one of the few that should be quick.

Wikipedia adds that downshifting through several gears in sequence, often called rowing, adds engine braking and sets the right engine speed for the corner exit.

Pedal feel matters for all of this. A Blayze newsletter recommends keeping the heel planted while braking (a heel stop helps) and wearing thin-soled driving shoes. Seat distance and leg bend are covered on seating and hands.

How it is learned

HP Academy and Driver61 both suggest building the footwork in a stationary car first, before trying it under track braking. Track practice belongs under supervision: Skip Barber Racing School teaches the heel-and-toe downshift in its advanced high-performance program, and a sponsored Motor Sport article lists race downshifting in its three-day racing school. A 2012 Motor Authority account of that three-day school describes instructors coaching heel-toe alongside line, throttle and trail braking.

Cars that do it for you

Some road cars automate the blip. Wikipedia cites Nissan's SynchroRev Match, first offered on the 370Z, which uses sensors on the clutch, shifter and transmission with an electronic throttle, and which the driver can switch off.

Left-foot braking

Left-foot braking means braking with the left foot instead of moving the right foot across from the throttle. Driver61 says that is its main benefit: the brake goes on sooner because the right foot does not have to travel. It treats the technique as advanced, usable all the time in automatics and paddle-shift cars, and in manual cars only in specific corners where no downshift is needed.

The cost is feel. Driver61 points out that most people have better sensitivity in the right foot, and if the left foot is weaker, right-foot braking is much better, because lost control outweighs the time saved. A left foot used to the clutch also tends to brake too hard at first, so Driver61 suggests anchoring the heel, pivoting the foot from it, and building sensitivity gradually.

Is it faster? The coaches disagree

Von Moltke also says left-foot braking on its own does not make anyone faster, and that trail braking is what separates drivers. Bentley, for his part, notes that either foot can be used to trail brake. Kart footwork is covered on karting.