With respect to the work you are doing, it seems absolutely pointless for you to call it "Citybus". Nothing stops you from calling it by it's real name. It is almost like it has become a trend to call buses "Citybus" and to remove their real branding. When selling products, obviously certain laws are put in place when it comes to using logos and design features made by a certain company. You aren't selling it (at least I assume you are not) so why bother creating confusion by calling it something it isn't.