You could have a wall or tree that fake kills itself every 10 seconds or so, then if a car drives into it it will be knocked over. You could not, however, have those bricks damage the car or be picked up.
Penguin slide :DMake a penguin out of bricks on a slide, and then have the bottom bricks kill. Sliding penguin :D
Then the vehicle would stop as it 'bumps' into the bricks before they're fake killed. My method would look better.