Shake at engine start, smart 42, 71 hp

In my 42’s I notice from the beginning a strange behaviour when starting the engine. As long as the starter rotates and the first ignitions start, the engine shakes relatively violently, at least this is unusual for me, since all my other cars have been running very softly. From the impression one could assume one or more engine bearings would be defective. During the further ride no hit or similar occurs. The mechanic of smart, to whom I explained this, would be He sat with me in the car and made several attempts to get started. Before I let the horse tell me something, I first ask here in the round if this is really “normal” and everyone has it.