What was the origin of the idiom 'Sunday driver'?

Answer 1

As car ownership grew and more families began to have cars, not all cars were used on a day to day basis for commuting and business. Some families used their cars for mostly pleasure purposes and did so over the weekend when they were not at work.

This meant that on Sundays there were a number of cars being driven round by drivers who were not used to day to day vehicle handling and indeed were traveling slowly to look at the passing scenery and "experience" the pleasure of being on their cars.

These drivers tended to frustrate the more experienced car drivers and the term was extended to describe any driver (on any day of the week) that seemed to dawdle on the road.