Does the oath of divorce (if it has occurred) not to re-book the first car include the second car (the GMC) that was booked later, knowing that the intention was to urge oneself not to re-book the first car, and that we follow the opinion of Ibn Taymiyyah that the divorce oath depends on the intention?

An oath is based on the intention of the one swearing it. Therefore, what the swearer intended by his oath is what is considered in determining its meaning. If you doubt whether or not you uttered the oath, then nothing is binding upon you, because the fundamental principle is the acquittal of one's liability, and certainty is not removed by doubt.