Normally, if you disable the replay taskbar, units will still keep their coloured icons above them, while If you disable the entire UI the icons will disappear but white stripes will appear on vehicles.
I just discovered you can take screenshots with both icons and stripes disabled, so the vehicles look as realistic as possible. If you disable the UI (Ctrl+U) before a vehicle enters the map, it will come in without stripes :
Note the little white stripes on the ambulance, which was called in before the UI was disabled, but no stripes on the E8.
Re-enabling the UI will make the stripes appear on the vehicle(s) in question.
Relic Entertainment
cblanco ★ 
보드카 중대 
VonManteuffel 
Heartless Jäger 
