If your playing Sims 2 or Sims unleashed or whatever, this would work.
In game, press [highlight]CTRL[/highlight] + [highlight]SHIFT[/highlight] + [highlight]C[/highlight] all at the same time.
Now depending on what game you have, somewhere at the top (or bottom, i forget) a rectangular box should appear.
Now type [highlight]move_objects on[/highlight] and then delete the car.
[highlight]move_objects on[/highlight] is a cheat for Sims that allows you to basically do whatever you want to characters or objects. If you aren't playing Sims 2, you can delete your character and when you click his face on the toolbar, he will reappear with full stats.
You can also build outside the original building square with this cheat (making houses bigger).
Now all your annoying honking should go away. If it doesn't, post back.