Try this:
-Select the track that you want to use
-Select the car that you want to use
-In the Upgrades-menu select the Upgrades that you want to use.
-If all Upgrades have been selected, click on the Button "Force Setup"
-Now a file for these settings on the selected track has been created in the ..\UserData\Settings\[Car name] folder
-Create the Vmod for your server and select the same track and car as before and install the Vmod
-Start the Dedicated Server creation, select the Vmod and check the "Fixed Upgrades" checkbox.
That's it. Upgrades should be fixed and also the AI should use the before selected and fixed Upgrades now.