Your dog is being that ... a dog.
I agree with martemchick ... I don't think the dog sees cars as prey ...
The dog is 8 months ... a puppy. I don't know very many dogs that are so highly trained at 8 months that they can be off leash in that kind of area. And even then, there's always a chance ... it's a dog.
If you want to keep practicising the recall off leash, go somewhere SAFE ... open fields, etc. And there is REAL prey there (birds, squirrels) that will really test you and your dog ... and it will help you realize if your dog really has high prey drive, or just likes to chase something because it's moving.
Marion’s Zoo-Kyleigh, Raylan-cat, Echo-TAG,