When I first got Project Cars, using my Xbox 360 controller the cars were super "twitchy" to say the least, I lowered the sensitivity and it improved but at speed the cars were still "twitchy" and hard to keep straight.
So I searched around and found some settings, and then experimented a bit myself, here is what I am using at the moment, it changed so much it took a few laps to get used to the cars "not" moving all over the place and having to move the thumbstick more on the corners but my times tumbled using it:
Steering dead zone: 15
Steering Sensitivity: 30
Throttle dead zone: 0
Throttle Sensitivity: 30
Brake dead zone: 10
Brake Sensitivity: 15
Clutch dead zone: 0
Clutch Sensitivity: 45
Speed Sensitivity: 75
Controller Filtering: 50
Force Feedback: 80
Advanced: Off
So I searched around and found some settings, and then experimented a bit myself, here is what I am using at the moment, it changed so much it took a few laps to get used to the cars "not" moving all over the place and having to move the thumbstick more on the corners but my times tumbled using it:
Steering dead zone: 15
Steering Sensitivity: 30
Throttle dead zone: 0
Throttle Sensitivity: 30
Brake dead zone: 10
Brake Sensitivity: 15
Clutch dead zone: 0
Clutch Sensitivity: 45
Speed Sensitivity: 75
Controller Filtering: 50
Force Feedback: 80
Advanced: Off