It's pretty easy money if you have a lazy 5 or more lazy hours over the 24hr period of the TC. Last TC I dropped the ball with paying attention and came up 12 laps short of 200GC running solo. To say my nose was out of joint is an understatement.
So, this time around I ran around brands Hatch every 2.55min for the first 4 hours. Got me the 40GC easy. I then started setting aside 15 or 30 minute intervals after that to keep myself well below the top 1000 for a sweet 200 GC(after my other prizes).
These types of TC's are really boring/repetative. So, what I personally do is set challenges within the challenge itself. The 500 TRC challenge became a matter of trying to set my fastest race time as I could get fully serviced. Best I got was a 2:51.9XX. I then set a challenge of my best unserviced time. Really pushing hard to get sub 3min. Best I got was a 3min250sec.
Many of these TC's are actually easy GC if you are prepared for such boredom. Ran a couple of times as a wild-card entrant, but I'll never get my head around carrying lazy arses in some teams.
These TC's arent about GC for me, as I have always hoarded GC and remain tight as a fishes bottom with delegating GC. Its about commitment, drive, grinding for the team for a rather small amount of time compared to overall game time