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Depends on weather conditions and how fast you are driving. I would want to pull the handbrake at 90 mph. Image

...Oh, you mean the software? Yes. Perfectly safe.

Hahaha. Unfortunately wet weather + favourite wide 90 degree corner + handbrake is how I found out that I am actually not a rally driving god in my younger days. I started off slowly and over the next couple of weeks would increase the speed and would push myself to do a better handbrake turn. Then one day I pushed it all the way into the pavement.
 
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