If a car jerks while driving, this is a strong sign of engine trouble. It could be caused by a spark plug malfunction, clogged fuel lines or fuel filter, a glitch in the vehicle's computer or from many other issues, according to HowStuffWorks. Regular oil changes and other preventative measures help to keep this from happening.
Cars often jerk when accelerating, after being left outside in cold, rainy temperatures. This is the result of moisture building up in the distributor cap, which produces an uneven electrical current, and the engine misfires. Leaving a car in a garage before rainy weather helps to prevent this from happening.
If a car begins to jerk more frequently over time, this could be from a vacuum leak in the fuel system.
If a car jerks all the time, regardless of temperature, a faulty throttle position sensor could be the culprit.
A car can also pull, which is similar to a jerk but is more gradual and is typically to one side. Like a jerk, a pull can be caused by a variety of issues, including the alignment, uneven tire pressures, putting a new tire into the rotation with the old tires, a torque steer or a problem with the brakes, if the pull only happens when applying them.