Why does the car shake when in D gear with the brake pressed?

[DiMichael]

When a car shakes while in D gear with the brake pressed, it can be attributed to the following two issues: 1. Insufficient engine power causing the shaking, such as when the engine displacement is too small, there is carbon buildup in the throttle, or poor ignition. The engine injects more fuel as commanded, but the additional power generated is insufficient to counteract the resistance from the transmission fluid. In this case, the normal operation of the engine is hindered, leading to slight shaking. 2. Transmission issues, such as hardened or aged engine mounts, can cause noticeable shaking when the brake is pressed while in D gear. The dangers of keeping the car in D gear with the brake pressed for extended periods: The transmission fluid inside the torque converter flows at high speed and is subjected to significant shear forces. If this condition persists for too long, the temperature of the transmission fluid will rise. Additionally, the engine will inject more fuel due to the increased load, leading to higher fuel consumption and an increase in engine temperature.