If fixed forward axi's is disabled - when your in chase view and go round a corner, the camera does'nt rotate with the too much, so if you go round a 90 degree corner, the camera only rotates by about 30-40 degrees (depending on speed)
if fixed forward axi's is enabled - it follows the back of your car by every degree, basically, its like a camera is hooked onto the back of the car by a camera mount or something :/
Its abit hard to explain, but if you wanna try it yourself, go into LFS, put the view on chase view, then go into options, view and then there should be an option about saying "fixed forward axi's | Yes - no
Give it a try.