Customised Cars on Time Trials?

Hi folks, been having a lot of fun with the parts selector recently and wondered if there is a way to use modified cars for time trials? In the time trial mode you can't access the parts selector or change what car you drive, and so far I haven't found a way to get modified cars to appear alongside the "stock" versions in the menu. Anyone know a work around?

 

Gameplay settings --> competative scenarios "off"

 

Thank you sir

 

Alternatively, you can make a config and save it and then go into the options and enable custom vehicles visible in the part selector.