Thank you, it is the Steam version with a couple of tracks and cars added but affects the built in cars I will try to zip and contact Steam.Is your GT Legends a fresh install or have you added any mods to it ?
I've seen this in the past with the odd vehicle, never all of them, and it was because of an error in that particular vehicles CAS file.
If you have the Steam version you may want to Zip up your current install and then let Steam verify all the files that are installed.