While true (beyond 30-50km/h), that assumes that cars are driving at a steady state. Obviously, cities with much more stop-and-go require more revving of engine

While true (beyond 30-50km/h), that assumes that cars are driving at a steady state. Obviously, cities with much more stop-and-go require more revving of engines. Acoustic tyres are also gradually becoming the norm, primarily with EVs. This cuts noise by several decibels. So it's not an unreasonable claim per se.