I took a crack at these earlier this morning (normal difficulty)...
Tsukuba - Nissan Silvia K's Dia Selection (S13) '90 - This took a couple tries. On the first, besides the aero that I'd added for aesthetics, I only upgraded the tires to SS, which brought the car just over 500PP. It was still too slow to gain on the leaders. On the second, I added all the 'sport' level enhancements (computer, air filter, brakes, suspension, etc). That brought the PP up to ~530. That at least made the car competitive. I finished P2, which was good enough for the first ticket.
Autopolis - Toyota 86 GT '15 - The only changes I made to the car were the aero bits, just to give it a sportier look. I was a little concerned going into the second lap in P2 that I might not be able to close the 10-second gap to the lead car, but the rubber-banding kicked in and I was able to take the win.
Goodwood - Porsche A/1500 GS GT Carrera Speedster '58 - I'm not sure if I've made any modifications to the car when I used it before. Regardless, it was on-pace with most of the other cars here, which made for a fun race. Finished in P2, way behind the lead car. Good enough for the second ticket.
Willow Springs - Suzuki V6 Escudo Pikes Peak Special '98 - This race did not go so well. I was off the track a bunch of times and rolled the car on the final lap. Finished in P5, way behind all the Gr.C cars. I'm not sure the Escudo is the car for me here. I'm no good at managing the turbo, or the extreme acceleration. I'm thinking I'll switch cars for my second attempt to one of the Gr.C ones.
Eiger Nordwand - Toyota 86 Gr.B Rally Car - I enjoyed this race. After reading the comments about how awful the track is in reverse yesterday, I decided to do some practice laps in Time Trial. That really helped for the race. Those switchbacks are tricky. I ran the race on RM tires. I pitted early -- lap 4, I think -- for fuel. That was probably too early. Worked my way up the field from there, taking the lead on lap 11. On my final pass by the pit exit I got low fuel warning with only 0.6 laps of it remaining. I short-shifted to the finish. The fuel ran out on the final straight to the line. Took the win.
The parts ticket gave me the shaft -- figuratively and literally -- for the Urus. We'll see what comes from the car ticket when I get it.