How do we get a four wheel drive

How do we get a four wheel drive

 

Can you be more specific?

Are you talking about the handling for a vehicle?

If by 4 wheel drive, you mean something like an SUV (i.e. the Police Patriot (GTA's "Hummer") used by the NOOSE teams in the default game), then you can get to choose it when you normally choose your vehicle. Just keep scrolling through all the available choices, it'll show up. Likewise, you can make it spawn by pressing the Tilde key (~), which opens up the console, then in that little screen that drops down, type " Spawn polpatriot " (without quotation marks), then pressing the Tilde key once again to make the console disappear.

 

Note that you'll get it if you didn't replace that vehicle with something else, otherwise, you'll get what you have put into that slot, though I'm gonna assume you didn't change any of the cars in GTA IV and kept it just like you had it when you installed it (I personally replaced my Patriot with the Police Yosemite someone made, it fits the flavor of how I have things set up a little better.)