NOTE: The traffic will be processed normally. The changes are only visual.
Viewing cars in all cameras, the same for pedestrians, is a good resource for better picture taking, useful for video creating and make your city appear more alive. The cars will appear very small on the maximum altitude camera, which make this just a detail. But for SC4 everything is about detail, right? However, it will make your game heavier in high altitude cameras.
On the other side, you can turn off all cars and pedestrians from appearing, without ruining any other graphic options, which is good for better perfomance, but bad for pictures.
I had included a picture as attachment but when the vehicles are not in motion, they are very hard to notice and I dont know how to create GIFs on big resolutions (if someone can do this please post on the comments with an example).
Ok, let get this done:
1) Go to your maxis Program Files folder (for example, mine is C:\Program Files (x86)\Maxis\SimCity 4 Deluxe).
1.1) Find your way to open the step 2 file with the notepad. If you already know how to do it, skip steps 3 and 4.
2) There is an archive called graphicrules.sgr, it can appears as "Graphic Rules" SGR archive type. If it is not there, it might be hidden. If you have just installed but never had run SC4 you wont see the file. You must had start the game at least one time to see it.
3) Select the file, then right click on it. Select the an option called something like "Open with" or "Open As" or similar ( my windows version is brazillian and the message in portuguese is "abrir como").
4) This screen below will appear. You have to select the notepad (the icon is a blue notepad). If it doesnt appear, you will have to look for it on the windows. If you dont know how to do that there are more detailed tutorials about it on the net, just google something like "How to Open with NotePad".
5) Now open the file.
6) Surprise! Not encripted. You will see several options. The first phrase you should see is "property groups for options set via the UI", with several # coming before it.
NOTE FOR ADVANCED SC4 USERS: I had not explored all things and stuff graphicrules.gsr can do. There are some stuff that can be explored that are not on this tutorial.
7) Look for:
# Sadly, we have no off"
What graphic options do you use on SC4? It all depends on it. Normally, everybody use high. Notice that for this to work you must know which option is selected for "Car Sims" or related.
8.1) If you want to make cars and pedestrians appear on all views, set "property minVehicleZoom" and "property minPedZoom" as 1.
8.2) If you want to make cars dissappear completely from view, set the same options from 8.1 as 6.
P.S. : There is an unconfirmed possibility that your SC4 is inverted on this rule compared to mine. For example, your camera "1" could be my camera "6".
9) Now save your file. It is recommended to have a backup of this, however, most SC4s will re-write this file automatically if it is not on the folder.
You probably be forced to "Save As" option and, when trying to replace the file, get "Access Denied" message. If that happens, move your old graphicrules.gsr to somewhere else then save the version you opened and edited with the exactly file name and make sure the extension keeps the same.
10) Open your SC4 to notice the changes. Everytime you edit this file you must restart SC4 to apply the changes.
I had not patience to explore this archive entirely and explore all its potentials. Be free to do yourself and to share your discoveries on omnibus and/or in the comments section.