In terms of transparency, I started putting a 3 ring binder in all of my cars with the following info.
1. The front cover has the as is sticker (i keep the binder on the dash with as is sticker in plain view)
2. carfax report including carfax price adjustment
3. copy of the 125 pt inspection
4. receipt showing what was repaired at independent mechanic after inspection
5. emissions test
6. vauto live market view report showing what similar cars are selling for
7. specs sheet on car
8. aftermarket warranty info and price
9. printout from yelp showing that I am ranked #1 in town with 5 star rating.
It has been a huge help to me, employees, and customers. Almost everything is covered right there and it has helped close sales.
This took me 1 day and $50 to buy the binders, plastic sleeves, print the reports, and assemble everything. I wish I would have done this along time ago.