Is there anything in the statement, "I didn't think that cars would stay for a long time to be resold in showrooms; I thought that cars would quickly be sold and other cars would come,"—knowing that the speaker did not intend to object to divine decree—that should not have been said?

Your words or expressions about what is in your conscience, or what you thought, carry no blame and are not related to objecting to Allah's decree. Many such instances are found in the sayings of the Salaf and in hadiths. For example, Aisha, may Allah be pleased with her, said regarding the incident of the slander (Al-Ifk): "By Allah, I never thought that Allah would reveal a revelation to be recited concerning my affair." We advise you to beware of waswas (whispers/obsessive thoughts), for indulging in delusions can be a cause of it.