Forza Horizon 3

The car is already set up to drift. I just threw it around the airport for about 10 minutes performing ultimate drifts till it popped.

I did this achievement on the large roundabout in surfers paradise. The car's doens't need any upgrades, just turn off traction and stability.
Afther a while you'll get in the flow and will do 2 or 3 ultimate drifts every circle.

I think HS Neofist's solution is one of the best. If you go on the big roundabout west of Sufers Paradise you can drift along and get the ultimate drift very easily. You don't need to do any tuning on the car, use it as it is. We made a short video showing how the drift should look like to get the ultimate drift often.

E-Drifts do not count for this. It must be a normal non e-brake drift. I used the Sweeping Drift Zone in the SE part of the main map near The Twelve Apostles and just kept drifting the bend in both directions until it popped. I used the "Best Drift Tune" by OG420DRIFTS but any drift tune should work.

My solution is for those drifting dummies like me myself, who have played the game for over 100hrs while haven't got 3 stars in even one single drifting PR stunt.

I tried HS Neofist's solution for some time and decide to give up because I cannot drive with the traction control turned off and made no progress at all...

So I move to the Hot wheels world, going to the half pipe at the north end of the Hot Wheels Island map. Here is the solution:

1. Turn the stability control and abs braking off, drive along the pipe and gain some speed. Speed is important, other wise the drifting may turns to burning tyres which is annoying.
2. When approaching a bend, drive a little left (right) to the suggested line if it's a left (right) turning, and turn left (right), no handbrake as it won't count.
3. Your car will start to drift with no obstacles to worry about, and easily get an "ULTIMATE" drift message on-screen, but hold until "Hot Wheels drift" prompt.
4. Do that at the next turning, you may get 3 or 4 Hot Wheels drift from one end to the other end of this pipe, so it's easy. I don't recommend reversing back to drift again at the same turning, because when the "Hot Wheels drift" prompt, it needs some cooling down to count.

(I got like 40 "ULTIMATE" drift as I traced it in the "record-technique" interface, but no achievements pop out. When turing to the xbox app on pc I found this achievement progress is only 60%.
The reason is in Hot Wheels world, "Ultimate" drift isn't ultimate, they added a new category called "Hot Wheels" drift, which can be obtained when holding the drift just a little longer.
I went for another 10 Hot Wheels drift and the achievement pop out. Even dummies can do huh)

For drifting dummies (like me who hasn't got a single 3 star drift zone) I found an extremely simple method:

I set up the car in AWD mode, with full power and upgrades, automatic shift and traction control and stability control ON and basically just drove in high speed circles in the area of scrub just north of the Outback Horizon Festival just 'nudging' the steering to initiate a drift and then holding a tiny amount of counter-steer.

Basically you just use the inertia from the initial high speed to maintain the drift.

Got the achievement within 10 minutes!

My tune is EasyAWDDrift by InterfaceLogic if any non drifters want a download and go solution.

For anyone who does not have this DLC
(The game and and all DLCs for it were taken off sale on 27th september 2020)

Step 1: Friend Don Joewon Song (This will allow you to do the next step and you can always unfriend later)

Step 2: Go to South Surfers Paradise Bucket list blueprint and select 'Drive the RX_7 Twerkstallion' by Don Joewon Song

Step 3: Either go to the large roundabout in Surfers Paradise or go to the airstrip to perform the ultimate drifts

The roundabout is closer, but I found the airstrip much easier.