When you drift in a curve it should stop drifting as soon as you drive straight ahead, but some cars like to Camaro ZL1 or Exotic Ride or Dodge Viper (and many more) don't stop drifting. For these cars you have to tap nitro to terminate drifting - this surely isn't like it should be. I consider this to be a bug and propose to change this in the next update.
Also sometimes drifting slows the car even more than not drifting.
And if you hit the wall e.g. Cairo 360 degree curve you keep touching the wall and literally stick to it.