Do I Need to uninstall the demo?

Hi folks, just got on board with this... I installed and tried the demo then bought the early access. (I rarely risk that with Indie projects due to a few letdowns, but this one shows a lot of promise and a ton of potential - to the developers, keep up the inspired work!).
Anyhow I entered the key (no additional downloading happened that I could see), and while I do see extra car bodies, engine blocks etc to choose from I get the impression I am not seeing features that many posts & the dev team videos lead me to believe should be in at this point. Eg: test track, the ability to add the engines I build to the cars I build... or am I mistaken? or maybe I just missed something in the game mechanics on how to access these features? Should I de-install / re-install?
Have tried a few forum searches and not (easily) noticed anyone else inquiring about this.
Tks,
Anyhow I entered the key (no additional downloading happened that I could see), and while I do see extra car bodies, engine blocks etc to choose from I get the impression I am not seeing features that many posts & the dev team videos lead me to believe should be in at this point. Eg: test track, the ability to add the engines I build to the cars I build... or am I mistaken? or maybe I just missed something in the game mechanics on how to access these features? Should I de-install / re-install?
Have tried a few forum searches and not (easily) noticed anyone else inquiring about this.
Tks,