There are a few quick ways for the paddock cruiser or spectator to determine if a car is a 1600 or a 1200 Formula Vee at a glance.
Most State Championship Regulations specify that 1200 Formula Vees should run a 100mm wide pink band on the front suspension and a 1600 car should run a yellow band (unfortunately this is not that strictly enforced).
All 1600 Formula Vees must run disc brakes front and rear so if the cars has drums it is definitely a 1200.
All 1600 Formula Vees run large aluminium dual port inlet manifolds and on narrow cars such as Jacers, Sabres, Stingers & Polars these are exposed from the bodywork.
If you are spectating at an exit from a slow corner the 1600 Formula Vees will appear to jump away from a 1200 Vees with the 1200cc cars typically catching them it at the end of the straight, as 1600 Vees have more power at the lower revs than 1200s but 1200 Vees tend to rev out better than 1600 engined cars.
Unfortunately CAMS rules dictate that all competition numbers must have white backgrounds with black numbers and that the area around the number must be kept clear to assist the officials and timekeepers so that they can quickly identify cars. So unfortunately Formula Vee is not able to do as go karts and motorcycles do and run various colour background and numbers to help the spectators.