I’d recommend reading the Valve Developer Wiki as it covers a lot of the important details for exporting models which you will need to know before trying to do something as complicated as a vehicle.
An overview of creating a model and getting it into the game: https://developer.valvesoftware.com/wiki/Model_Creation_Overview
Some Vehicle Specifics: https://developer.valvesoftware.com/wiki/Vehicles_(modeling)
The way I learned to make vehicles was basically to examine the models valve had made, like the HL2 Buggy and reverse engineer them. I pulled apart their .qc files and found out what parts were responsible for animating the model, what parts were for the physics etc.
As for your steam message I would love to make a proper video tutorial but right now it’s very difficult to find the time, especially since I’ve now got a job. Once the training is over I may have a better idea of how much time I can spend on this. I shall be finishing the Pontiac Grand Am first and releasing it before I get side tracked with any other jobs.
What I really need to do is actually break down the whole process again and re-learn a few things since I’m actually quite out of practice, it’s been a long time since I last rigged a vehicle from scratch.