Here's a purpose built Smart ForFour, carbon fiber widebody, roll cage, and a 2.0L 4 cylinder turbo engine producing 600hp. It looks like it loves the kitty litter.
The Insurance Institute for Highway Safety tested the Smart Fortwo and found that it protects it's passengers pretty well. Both front and side impact ratings are Good.
Since airbags, including the side curtain, are standard on Smart cars, they are safer and less expensive than a Toyota Yaris. $2730 or so will get you side airbags for the Yaris, it's free with a Smart.