The main information regarding translating the CarDealer theme and other themes could be found in this post
As for translating the quick search please note that .pot are located not only in the theme root but also located in all theme plugins and in this post we are referring to the quick search widget that appears on the slider and the pot file for it is located in the wp-content/plugins/tmm_content_composer/languages/
So once you are in the Loco translate scroll down to the plugins, add required language to the Content composer and you will find all required elements there
