N does not improve things that much. The tech put it in every gear: P R N and D. He hit and released the brake pedal, to see if the hydraulic power brake assist had anything to do with it. Vibrations persisted.

Turning on the AC actually makes it slightly better. He concluded it's a normal thing, where the alternator has to try and cope with different electrical demands.

Thankfully, I shut the engine off at longer red lights (>45sec) thesedays due to higher cost of fuel in order to minimise fuel consumption. That puts a definite end to the vibrations.