You didn't specify a speed, so I'm curious how fast are your suburban back roads? I've seen signs from the US that show 40mph speed limits on purely residential back streets which is already faster than I can drive on literally any street within my city.

Residential roads here are max 30km/h (18mph) but also often 20km/h (12mph). Slow enough that the EVs should produce less noise, even though both produce tire noise.

Out of curiosity, where are you driving that 20km/h is a common speed limit? Is it actually respected?

40km/h where I am. Below that is only seen in shared traffic areas (basically pedestrian areas where cars are allowed to pass through).