Days in stock is the number that matters. Cost, reconditioning, days on the forecourt and current price on the same record show which car to move now rather than at the end of the quarter.
Reconditioning costs are what turn a good buy into a bad one. Recorded against the vehicle as they happen, the real margin appears before the car is sold rather than after.
The paperwork travels with the car: transfer, checks, warranty, previous owners. Held by registration, a question two years later is answered in a minute instead of a search through folders.