If you expect your request to be seen a little more, you need to have a more innovative title, a more reasonable description (and an understandable one too, for that matter), and you also have to specify specifics, say for a presidential limo (much like your request).
You need to provide details like
*Particular driver, if it's a request for a vehicle owned by somebody.
*Make model, and year of the car.
*Engine specifications (these the modders can get themselves but it saves them less time because if they have the numbers they can take those into decimals (which I recall how handling lines worked for GTA 5.), and make the car act like the real thing.)
*Problems with the model, that may need to be fixed (this doesn't mean you can spew 10,000 shit models for modders to fix, you won't get it every time. If you're this desperate, find a highly dedicated modder.)
There's more you can ask for, whether you want bits and pieces added or not, whether you want tuning or not, etc...
However, don't expect most of it to fly with other modders, maybe the specifcations and make and model of the car, but if it's tuning, or if you want bits and pieces added, some of them just won't do it.