Why does it occasionally shake?

Congratulations, you're about to replace the cylinder head. This is a common issue with Jetour engines.

When the engine isn't running, the vibration seems to be caused by external forces. You can feel the vibration when there are people in the car, on the road, or when heavy vehicles pass by on a bridge!

2.0 or 1.5?

Not during the start-up.

When starting a cold car, the engine oil hasn't fully lubricated the system yet, so some shaking might occur. This is normal.