Cars with manual transmissions comprise only about four percent of all vehicles sold in the United States, so it is becoming rarer to find American drivers who know how to drive vehicles equipped with them. Even more so, fewer drivers understand how to operate a manual transmission in such a way to protect its components from premature wear and damage, especially those who only have their driving permits. Below are four things that all drivers of cars with manual transmissions should do routinely. If you follow these guidelines, your car will last longer, drive better and cost you less for repair and maintenance:

Keep hand off gearshift knob unless you need to change gears

A seemingly harmless habit that causes unnecessary wear and tear inside your transmission is resting your hand on the gearshift knob during driving. To understand why this habit can cause damage, you need to understand how the shifter knob manipulates the gears.

At the end of the gearshift linkage lies a shifting fork; this device intersects the gears and slides them into position as you move the knob. The shifting fork is in close proximity to the spinning gears, and even a slight amount of pressure can cause the fork to make contact with gears. Of course, the short, intermittent contact between fork and gears during shifting is normal and doesn't cause undue wear. However, by resting your hand on the knob, you are unknowingly directing the fork against the side of the gears, thus causing friction and wear to both components.

If you find it difficult to break the habit of resting your hand on the gearshift knob, attach a small strip of Velcro hooks to the top of the knob. The slight discomfort caused by the Velcro will help remind you to remove your hand from the knob and place it on the steering wheel.

Rest left foot on floor, not on clutch pedal

Another bad habit that manual transmission drivers often find themselves practicing is leaving their left foot on the clutch pedal during driving. As with the shifting fork, even slight pressure on the clutch pedal can cause the clutch to disengage. The disengaged clutch pushes a small device known as the throwout bearing against the diaphragm spring, and this places mechanical stress on the bearing as a result. Throwout bearings can handle intermittent disengagement, but constant pressure will eventually lead to a component breakdown. That is why drivers should consciously place their left foot flat on the floorboard except when shifting.

Use brakes instead of engine torque to hold your car on a hill

A common habit among drivers of vehicles with manual transmissions is using engine torque to hold cars on an incline at stop signs or traffic lights. However, this is also a practice that should be avoided by drivers; attempting to "feather" the throttle results in a mismatch between transmission speed and engine speed. This mismatch causes the clutch to rub against the flywheel and ultimately wear the clutch to the point of replacement. If you drive in a hilly environment, avoid the temptation to use your engine's torque to keep the car from slipping backward on a hill. Instead, use your vehicle's hydraulic brakes to prevent rolling, or learn to use the emergency brake if the slope is steep.

Avoid sudden acceleration while in higher gears

The last potentially damaging habit practiced by drivers is attempting to use sudden throttle applications while in high gear. For example, instead of downshifting, drivers will often just press the accelerator pedal harder while entering freeways or while passing a slower car. This practice is known as lugging the engine, and it can wear the clutch of your vehicle. High gears allow the wheels to rotate at high revolutions per minute (RPM), while the engine's flywheel is turning relatively slow. Whenever a driver suddenly increases the the flywheel speed, it creates a speed mismatch between engine and transmission, thus placing a strain between the clutch and flywheel. Any strain between the two will cause premature wear of components and ultimately lead to a clutch replacement. Always downshift when you need to increase acceleration, and only use high gears for cruising at a steady speed.