I know I am late but to any of those just picking this DLC up or the platinum hits as of 1/25/2012 this glitch still works even after the update. I'm currently at 200,000 points. I purchased the platinum hits version used off of Amazon.
I did some rough math if you do not tape or find a way to hold down RT to hold down the throttle of the car you will do about half a mile every two minutes. However, if you hold the RT button all the way down you while do roughly a mile an hour or 60 miles an hour. Which will take you about 17 hours. But while I'm away at college I'm getting achievements. I thank the OP for this method. Saved me a ton of time.
I will update and let those know when I get the achievements.
I got the achievement for one million points. It took about 4 hours as others have stated. So the glitch works great. I'm letting my xbox run to build up miles driven for the other achievement.
Last edited by jkbd33; 01-25-2012 at 04:45 PM.