I wonder what make/model car Marko is talking about? Engine on/off on our 07 Camry Hybrid and 12 Prius were virtually seamless too.
I think the difference is the hybrid battery. The car shuts off, then on rolling again it's the hybrid battery that initially moves the car. Then over 7 mph (or whatever) the ICE starts up and off you go. My Volvo wagon is a bit rough on start up. I think that is the evolution by Volvo to the hybrid/electrification of the entire model line
I was reading last night that the newest Volvo have an airbag on the exterior. So if the car hits a ped or cyclist the airbag inflates so the victim doesn't hit the hood or wind screen hard