One state, two competitive situations
The Chicago metropolitan area is one of the densest retail automotive markets in the country. A shopper in the western or northern suburbs can physically reach a dozen rooftops in an afternoon and can message all of them from a phone in a couple of minutes. Downstate, from Rockford through Peoria, Springfield, Champaign and toward the southern counties, the catchment is wider, the store is often the only realistic option for a given brand, and repeat business carries much more weight.
Both are good businesses and neither is won the same way. Metro stores lose deals in the gaps between an enquiry and a reply. Downstate stores lose them on trade values and on how the last purchase was handled. Reporting the two together produces a state number that tells you nothing about either, which is why the pipeline split is worth doing before anything else.
The average response time hides the problem
Almost every store that measures reply speed discovers the same shape: the median is respectable and the tail is dreadful. Weekday daytime leads are answered quickly because somebody is at a desk. Evening and Sunday leads sit, and those are precisely the hours when people shop for cars.
Measuring per source and per hour turns that from an argument into a staffing decision. It is difficult to justify a Sunday evening rota on instinct and straightforward to justify it on a chart showing where the leads went unanswered.