Well you kind of have too. Steam automatically updates games. Unless you got the game somewhere else...
Okay, my bad! It showed up, but there's another problem. Whenever I press the Forward or Reverse arrow key, the car fails and doesn't work at all. And when I respawn it, it doesn't worl either..
Woah now, you didn't even give the guy a chance to respond as to why he is at 0.10.3, If I remember correctly, you used to be able to buy the game off the website, and not through steam, thus not automatically updating the game. I think you had to come to the website and download the latest version/update yourself. Edit: Let's try to calm this down, before mods have to come and get involved.
Okay, my bad! It showed up, but there's another problem. Whenever I press the Forward or Reverse arrow key, the car fails and doesn't work at all. And when I respawn it, it doesn't worl either.. Umm.. It works eventually. I accidentally put the "Hoverside" file in the Hopper file
the mod is outdated, that i think is the issue, because i get that to. Try disabling all your mods but this one, that may or may not fix it.