After many, many, MANY expletives I've finally got gold with this car random set of numbers in a spreadsheet.
DS3 novice settings
Transmission: Manual [allows you to hold a specific gear to limit speed]
Driving Line: On
Active Steering: Strong
Traction Control: 8
Active Stability Management: Off [turning it On makes the car less stable!]
ABS: 3 [always wondered...why isn't this one spelt out? Anti-Lock Braking System (ABS).]
Controller Steering Sensitivity: 5
This allows you stab the brakes then point it around each corner, easing on a tiny bit of throttle. Then, when the track straightens, full power!
I only use the Drag Reduction System (DRS) on the very long final straight. I return to normal mode just before the bridge. Then I coast until the straight just before the final hairpin. Tweak and wiggle the steering as needed through this section - the aero and electronic aids mean you don't have to be smooth. (A dab of brake before the slight left-right chicane can help your confidence.)
I drive most of the track in 3rd gear, as recommended earlier. After one valid but slow lap I'll start adding 4th in a few places. Once I know where I can and can't do that, I do another valid but slow lap. Then I try for a better careful time. (Still being very, very careful.)
Gradually I learn where I had to be ultra slow and where I could merely be very cautious. Never pushed the car. Never, ever push the car in high speed areas!
Lots of coasting in high speed turns in 4th. 10% throttle stabilises the car through corners and seems to increase steering a bit.
Give it a big, BIG stab on the brakes before ANYTHING that looks like a corner. With 2,500bhp you can get the speed back in no time!
My time was an entirely unremarkable 4m44.654s and the gold target is 5 minutes. Just fast enough for the 1.1 million credits a Gold gives, on top of any other awards you may already have.
"Win at the slowest possible speed."