California Drifter Achievement
Finish the California Drifter Rivals event having earned 15,000 drift points in one lap.
This must be earned in a specific Rivals event. From the Forza Main Menu choose Rivals -> Drift Rivals Event -> California Drifter. You are permitted to use the rewind feature without voiding the achievement. You will want to turn the Drift HUD on in the HUD options (found in the Forza Profile menu) before entering the Rivals menu.
While it can be done with a variety of vehicles if you modify and tune them to be a drift car, you can be successful with a stock vehicle as well. You are restricted to RWD vehicles of no more than 600 horsepower.
If you are looking for suggested vehicles, at the event selection screen you can press to view the leaderboards. You can check out the various vehicles used by different people and if you press on any given leaderboard entry you can watch a replay of that car being used to get the points posted. I would suggest watching several of them to get ideas on where to start drifting on each turn. While you don't earn drift points on straightaways, note that many of the top drivers start drifting before the turn so that they get maximum points once the corner starts.
For assists use the options below:
Suggested Line - Full
Braking - ABS Off
Steering - Normal
Traction & Stability Control - Off
Shifting - Your choice, although manual will give you more control if you are comfortable with it
Damage, Fuel, & Tire Wear - Cosmetic
If you are going to mod the car, definitely put on Racing Brakes and upgrade all of the drivetrain and engine features to their maximum. I also would suggest putting the rear tires to a wider tire and a stickier compound. From a tuning perspective, less pressure on the tires and dropping the suspension as close to the ground as you can are both helpful. Also, set the differential to 100% and change the balance of your braking force to be more toward the front than the rear. A video of someone walking through changing a car into a drift vehicle is below, and while he is working on a classic Ferrari, the tips he talks through are useful in general.
Before attempting the achievement, I strongly recommend taking several laps around the track in your car with all the settings/tunings/mods set the way you are going to make your achievement run. Getting acclimated like this will make it much easier to actually do the drift run. If you want to build up to it, do another couple of laps where you just kick the back tires loose as you round the corner so you get a small drift, which can help you learn how to recover from the drift without hitting the walls. Once you are comfortable with the car, then it is time to make a serious effort at the achievement.
For the actual race itself, look at your score after each corner to see if it is reasonably close to the numbers below. If it isn't, press to rewind and try again. Also note that after you bank the points from a drift, you can stop, back up, and set yourself up for a successful corner ahead if you want, although obviously it isn't necessary if you are good at drifting. You can't repeat corners over and over again to build up points, but you can essentially stop to plan after each corner if you wish.
Turn 1 (gentle left) - 1800
Turn 2 (right, around flowerbed) - 1500, total 3300
Turn 3 (90 right) - 1700, total 5000
Turn 4 (90 right) - 1800, total 6800
Turn 5 (sharp left) - 1900, total 8700
Turn 6 (90 right) - 1900, total 10600
Turn 7 (90 right) - 1800, total 12400
Turn 8 (extended left) - 1800, total 14200
Turn 9 (hairpin right) ** Note you can link this drift to Turn 8 for more points - 700, total 15100