1. Add user Id in vehicle. (open vehicle in which you want display Agent - choose tab Seller Contacts and add ID in field OwnerID)
2. Go to modules - Simple Membership User's Profile and choose position for module and make it publish. Assign module with menu View Vehicle.
3. Check in Plugins - Simple membership and Vehiclemanager, get vehicles, it must be publish
4. Edit Agent profile you can with help Simple Membership. Go to components - Simple Membership: Users and choose your agent/seller. Add profile image and all other information.