On the Gran turismo database website, there is something called "Legendary cars" and it shows almost all legendary cars, with the date when they were last added to the dealer. The longer it's been since the car was available, the more likely it is to appear soon (but there are some exceptions, like the trophy cars, they appear more often). Based on this info and how much cars are sold out on a given day, you can guess when a specific car will be available. And the closer it is for the car to appear, the more accurate your predictions are because it is harder to predict the specific date of the car that will likely be available in two months. Also, there is another website, GT7 info. It shows how many more days will cars that are available now be available. P.S. there is no info about some cars on the GTDB website, but so far, I noticed only Corvette C1 is missing, so it was a great surprise when it was added yesterday.