Speed decides most of it, and everyone knows that and still loses on it
A person enquiring about a car has usually enquired about the same car at three dealerships within the same hour. The one that reaches them first, with an actual answer about availability and a specific test drive slot, gets the appointment, and the appointment is what converts. Nothing else in the routine matters as much as the first hour, and nothing else is as consistently mishandled, because enquiries arrive in the evening and the team is on the floor during the day.
So the routine begins with a very boring discipline: every enquiry is owned by a named consultant the moment it lands, there is a visible list of enquiries with no contact attempt, and the sales manager looks at that list at the end of every day. Showrooms that do only that improve before they change anything else.