Bikes are far, far cheaper to insure. (About a tenth for me on any like for like comparison. 125 against Nissan Micra, Bandit 12 against Subaru Impreza). 
  
But, you are 14. I'd recommend trying to keep your mind open and just saving what you can. Don't worry about car vs bike until you're old enough for either of them! 
  
And don't bother with a 50cc anything at 16, they're all wank.