This is the big four if you're new to researching:
Acceleration
Braking
Handling
Downforce
If your car is maxed out with these, your car is called the "The ABHD Maxed Out Car". For leagues, call it "The ABHD Maxed Out cars", or "the track masters".
The other four are:
Tyre economy
Fuel economy
Cooling
Reliability
If your car is maxed out with these, your car is called the "The TFCR Maxed Out Car". For leagues, call it "The TFCR maxed out cars", or "the conservation masters".
If you maxed out completely, your car is called "The Maximum Car". For leagues, call it "The maximum performance cars".