This stupid idea of maximum 20 miles per hour

in my opinion.
First, there will be more "silent" cars coming onto the roads with more people buying electric cars,so whether a car is being driven at any speed,cars are not going to be heard.
Its okay to say that less pedestrians are killed or injured at lower speeds,the downside is the pollution levels go through the roof. If cars are in the lower gears,this then leads to more people suffering from asthma attacks.