Turning and Braking

Whenever I play this game It is hard enough to keep the car in control when going straight but the really tough part is turning. I used to just try to turn without braking and would sail off into the wall every time. I figured out that GT4 doesn't have automatic braking help like the NASCAR games I am used to playing. So I started braking in the turns like a video I saw on youtube and SAME THING! I go sailing off course. unless I slow down to one MPH and turn It doesn't run off but all the other computer cars just keep going and don't need to slow down around turns. Real cars don't need to slow down to one MPH just to complete a 40 degree turn. Never had this problem on classic racing games like the original Gran Turismo or Top Gear.