Thanks for the explanation. So when the  feature_extract parameter from this tutorial 9 is set to True, only the last layer is updated, but the other layers still contain information that might be useful.
So would you say that if you have a small dataset, having the the feature_extract parameter set to True would generally yield better results? Specifically if you have classes from the original domain the pre-trained model was trained on, like in my case where I have car and background?