My 02 I35 has a smooth ride for the most part, but Ive noticed something feels loose like in the front wheels. Also we recenlty had bad weather lots of rain and ice. The car handled terribly in the rain like the it had a mind of its own, it would go where it wanted to so i had to grip the wheel and go extremely slow, other times it would drive great. Shop just told me that the control arms were recently replaced when they did an oil change. So i dont know it an alignment would cause things to feel loose or out of whack or what.

 

Bad alignment, tires or suspension parts.

Jack up the front end and give everything a good tug. Some shops do free alignment checks and give you a printout. Run your hand over the tires and check for irregular wear. This can cause dangerous handling in inclement weather.