Question about Scripting

Hi everyone, 

I'm trying to work on a script and I'm running into some problems with it. There are a few things I can't seem to figure out. Here is what I need help with.

I need the script to check if the player owns a vehicle and it is stopped and the player is outside the vehicle. I know that LCPDFR adds a blip for the player's vehicle. I want to be able to have the script check and see if the player has a personal vehicle by checking for that blip and if the blip exists, to run the script. But I don't know what the argument for that is or if there is a flag for an owned vehicle, and if it can be done outside the API. (I don't want to do it in the API, yet as I have no idea how to use it.) Can someone help me? I would greatly appreciate it. That seems to be my only problem now. I'll see if anything else comes up.