What are the reasons for severe engine shaking in a sedan?

[DiRuth]

There are four main reasons for severe engine shaking in a sedan: 1. Ignition system failure. Solution: Check if the spark plugs have excessive carbon buildup, and clean or replace them immediately if necessary. 2. Worn or loose engine mounts. Solution: Replace the engine mounts. 3. Carbon deposit issues. Solution: It is recommended to take the car to a 4S shop for engine cleaning. 4. Poor fuel quality. Solution: Clean the car's throttle body promptly. If the issue persists, take the car to a 4S shop for repair. Always refuel at reputable gas stations, use the fuel grade specified by the manufacturer, and perform regular maintenance.