I dont know if this is normal but ever since i got the car with 90 miles on its shakes when i brake at hiway speeds,ive been real easy on the brakes and now has 500 miles on it and isnt better,should let it go? Is this normal? Should i give it some time? I wouldnt think rotors are warped already? Been on lot for almost 200 days before i bought,

 

It's probably a warped rotor. Take her in, and let the dealer have a look.

 

sounds like a trip to the dealer is in order . . . . but if you are trying to avoid that, you could try "bedding the brakes" in case it is some kind of rust or contamination on the rotors . . . . Google can find it and explain it better than I can