Ugh i just wonder how cars are fitting in the rp.... i do not want to be a douche here but in a world being run by magic...cars running by fuel....gas or anything else would be much unlikely. It would be close to FMA or Fairy Tail. There are transportation means but with pilots running the monopole i think they would want to maintain it and people would not complain.
In a world where cars are run by tech users why would someone then create a car running on NOT ever lasting fuels.
Sure the magicans would be in need for tech users then but it would fit in the lore....while i am doubting a red pick suddenly driving through a more MTG based lore >_>

Then for the whole stamina thing..i do like the thing stamina over sheer power but in rp fights it tends to be really unfair. Just a huge opening attack will destroy a Tech user completly and with magic being able to enchant weapons, to be manipulated by thoughts and to be controlled more freely i see a huge disadvantge in being a tech-user.
A tech can just do what it was designed for... Like shooting a lightning...like creating a flame... a mage which would specialize in being a fire mage could do more! The whole thing about stamina would then be completly useless since creative and unknown patterns would then win.
I am not trying to change your rp here, i am just trying to get more people in being a tech user ....which is currently only me.....because i see a huge lack in being a tech user....