Like it says, I have the F100, but don’t have the new mustang or nothing. How do I get these?
The vehicles you are referring to are from the Forza Horizon 2 Launch Bonus Car Pack. Do you have this add-on content completely installed? If it shows installed, try performing a complete console shutdown by holding the Xbox One power button (not the controller’s) until it turns off. Reboot and return to the Autoshow to see if the Launch Bonus Car Pack vehicles are now available.
I’ll try that. I shut down the console every night but I guess this is a reset of some sort?
Yes.
Make sure all the content is properly installed.
Then, you must still go into the autoshow to purchase the car (for free) if you have the corresponding DLC.
The Launch Bonus car pack should still be out there free of charge, however, you are most likely out of luck on the day one DLC. (Three bonus cars with livery - though I’d say the non livery versions are better).