why cars rated fair deal vs good or great deal

The lower the price compared to average the better the rating. The numbers are there if you bother to look.

In my research (very extensive), the above answer is incorrect. There is no consistent price threshold, that once crossed, moves a price point from fair to good to great. And there in lies the problem. In a given search parameter, one vehicle that is priced $1500 below market value is deemed a Great Deal, yet another vehicle is priced at $2000 below market value and is only deemed a Good Deal. How is that even possible. So if you check the box "only show me Great Deals", you could be missing out on better deals. Very flawed search engine.

I have noticed some cars say fair deal while others say good deal and the price being sold compared to the milage is essentially in the same range. Without only paying attention to price and mileage, I believe the VIN numbers attached to these vehicles play a huge role in how they score. Getting a car at a good price with low milage is great and all, but what about the things you don't see? Factors such as maintenance, how many owners the car has had, and if the car has been in any accidents are just some of the very important keys on making a final decision.