General Advice for All Race Styles:
You can usually live with out ABS if you set your brake bias and brake pressure correctly. ABS keeps your tires from locking up, if you set your breaks correctly you can do this much better with break pressure, then use the e-brake if you do need to lock the tires.
For Nissan Speedway, you can set negative camber to get extra grip along the long curves.
Power to weight is the single biggest factor in your 0-60 time.
Aerodynamics is the single biggest factor in your 100-180 time, and your top speed. I was blown away that the Lancia Stratos could be made to weigh 1600 pounds and with 250 hp only do 161 miles per hour, and the 1900 pound Mini would do 168 miles per hour.
Adding a Spoiler, Certain Differentials, wider Rims, and upgrading your transmission can all lower your PI, so if you are right on the edge of a Class Barrier, and need to shed 3 or 4 PI these upgrades can drop you enough to qualify. This is especially useful on a course that doesn’t tax your top speed.
If you build a fast enough car you can let the computer run endurance races and quickly pocket 50,000 credits while you sleep, but make sure you use a wired controller or it will fall asleep, and pause the race.
Nudging some one in to the pit row will make them go very slow for a section of the track. This is really mean, but can be quite effective.