If you do not own the Black Market Delivery or Keys to the Map DLC, a verified save may still give you the cars, but they might appear as "locked" in customization. The save works fully with the base game, but DLC-exclusive visual parts require your own purchase.
Navigate to your Documents\Need for Speed Heat\SaveGame\savegame folder. Delete the existing file named 1 . nfs heat save game all cars unlocked pc verified
To unlock all cars and reach 100% completion in Need for Speed Heat If you do not own the Black Market