Forza Motorsport 5

If you're having trouble getting perfect turns, try turning on assisted braking and the suggested line to full. Assisted steering is optional. This way you don't have to worry about braking (the game will brake automatically for you) and focus solely on making a turn following the suggested line. Also, take it easy on the gas while making your turn. You don't need crazy speed and if you start squealing the tires and drifting you likely won't get a 'perfect turn'.

You won't be posting your best lap times with this method but it makes it much easier to put up several perfect turns throughout each race.

The following method can net you around 4-5 Perfect Turns each lap which last about 20-25 seconds.

Settings:
Track: Long Beach - West Route
Car: Any ''F1'' type car for their speed and handling. I prefer the 2013 Chevrolet DW12
Laps: As much as you need (up to 50)

Assists setup:
-Suggested Line: Full
-Braking: Assisted
-Steering: Assisted
-TCS & STM: ON

Here's a video I've made as an example!

If you think there's something wrong with the solution, please leave me a comment and enjoy your new achievement.

I found that I was getting a lot more "Perfect Turns" when I was using the Lotus E1 Formula 1 car, and any of the P Class Le Mans cars. I wasn't trying any harder, but it seemed like these cars stuck to the road better and allowed you to get a better line round corners