Haven't been playing in a long time, but recently I was bored, so I loaded the game up.
Finally broke into the 21s.
Time: 21:58
Fastest lap: 1:45.2
and I got the Clean Race Bonus, too.
825,000 credits in under 22 minutes.
This tune uses FM1 and one stop after lap 6. Don't change tires. (the rear will be red after one lap, don't worry about it)
I shift somewhat short for the higher gears, and occasionally switch to FM2 for part of the long straight depending on my fuel situation. I ran out of gas just as I was entering the pit, and just as I was crossing the finish line.
I use TCS0, as it seems to be best for wall-riding, but big slippages will drain your fuel, so ease off the throttle if your tach is hitting the limiter.
I shared a video of my run within GT7, but I don't think you can watch that except in-game at the showcase. The title is "WTC600 Tokyo 825k in 21:58".