The lists in the upper part of the window show all the categories that are available for this data. Click on any of the list items to select that category, and consequently select all the cars that belong to this category. Selected cars are shown in red.
If the list has more items that can be displayed, then a scrollbar will appear along the right edge. For a better overview, all selected items are also marked inside the scrollbar. For faster navigation between selected items, right-click on the up- or down-arrows of the scrollbar. The cursor will then jump directly to the next selected item in the list.
If you would like to work with only a subset of the data, then click on the little filter icon to the left of a list item. All the cars that do not belong to this category will then be filtered out (represented as greyed-out, not active anymore) so that you can concentrate on your objects of interest.
In summary:
Use selection to quickly mark something: click on the label.
Use filtering to concentrate on a few cars and remove those that are not of interest: click on the little filter icon to the left of each label.