This worked for me:

Create a text file in YourServerName>CommunityOnlineTools>Vehicles
Name the file whateveryouwant.json
Insert

{
"VehicleName": "OffroadHatchback_Blue",
"VehicleName": "Ada 4x4",
"Parts": [
"SparkPlug",
"CarBattery",
"CarRadiator",
"HeadlightH7",
"HeadlightH7",
"HatchbackDoors_CoDriver_Blue",
"HatchbackDoors_Driver_Blue",
"HatchbackHood_Blue",
"HatchbackTrunk_Blue",
"HatchbackWheel",
"HatchbackWheel",
"HatchbackWheel",
"HatchbackWheel"
]
}

Only problem I have is that when you go to the Vehicle EX in the Menu it does not give you a title for the vehicle but it lets you spawn it in on the cursor. The file name for the item needs to be placed first as can be seen in OffRoadHatchback_Blue. Make sure when you're adding your own vehicles to keep with the same format including all "" and using the commas and brackets.

Thanks dude, this worked for me also!