In GTA IV on PC, you can activate the police lights and sirens by pressing the "H" key while driving a police vehicle. This will turn on the lights and activate the siren. You can also use the siren for different sounds by pressing the "Q" key, which cycles through various siren tones. Be mindful that using these features can attract attention from other pedestrians and vehicles in the game.
No. There's nothing requiring police to use any particular color of light, or to use a light at all, as long as their intentions are clear.
You can't use your directional only pedestrians can.
no, you can't
no
press select a couple of times.
you not allowed to use it stupid all cops chasing you
You are only able to drive it, as the lift will not work.
you mean the weather cheat, it's hot-555-0100 i believe. use gta4.net for the hot number if you don't know it.
you cannot use nitrous in the normal gta 4, but you can on TBoGT in a race
use gta4.net's interactive map
It shouldn't.
This varies in different countries. In the USA, it is allowed in few states but banned in others. As the police in many countries use blue light on police vehicles then blue is not allowed on private motorcycles.