Engine braking is most effective when the transmission is in lower gears and the engine is near the governed RPMs. Which statement is correct?

• A. False
• B. True when the engine is at idle
• C. True
• D. Not applicable

Answer: (C)

Engine braking comes from the engine’s resistance when you let off the accelerator and the throttle closes. This braking effect is strongest when the engine is turning quickly, which happens in lower gears because the same road speed means the engine is spinning faster relative to the wheels. When you’re in a lower gear and you lift off, the engine has to slow the drive shaft down, and the higher the engine RPM, the more braking torque the engine provides. If the engine is near its governed maximum RPM, it’s turning fast enough to produce substantial resistance, giving you the most engine braking. At idle, the engine is turning slowly, so there’s very little braking effect. So the statement is true.