I was able to complete all of these races with ease (well, Toscana was not so easy: more on that in a moment). Looking through my garage, I found:
Spoon Integra Type R (DC2) '99. 216bhp 1080kg.
At 415pp, a win with this car still gives you a fairly hefty Performance Difference Bonus. The Fixed Sports Suspension (standard on the car) is an advantage, naturally. Fine handling. I breezed through all of the tracks, winning first time, with the exception of Toscana: the night-time conditions badly affecting my second and third lap times. The way round it for me was to ensure you could always see a set of rear lights ahead to show the way. That, and learning to circuit a little better. Got there in the end.
This morning, just did Trial Mountain in the Toyota MR-S S Edition '99, that is currently in the OCD; 138bhp, 970kg, 377pp. Great race, caught the rabbit (Celica GT-Four '91) on the last lap, at the start of the back straight. The light weight and great weight distribution means you can carry plenty of speed through the final chicane, up over the rise, through the tunnel and into the hairpin. Having to be creative with the 'mobile chicanes', as ever.
Total race time: 9:07.702, fastest lap 1:47.909 (I'm not the quickest!)
Edit: Oh, and for this race, this car combo: $1,779,750, and 174,020 exp. points.