I think I figured out these cars and their relative strengths/weaknesses.
They are all understeer dogs. A good way to combat understeer is to move the center of gravity back (you should all put your ballast at the very rear). The car that has the most weight on the rear axel will generally handle better. Looking at the cars I have, they have the following weight distribution with the ballast all back.
Camaro: 43/57
Vette: 44/56
Masserati: 44/56
BMW: 47/53
Jag: 52/48
Dodge: 56/44
This is a good order in how the car handle.
The Camaro is very fast in the last sector, but it has low top speed. Still it might be the quickest at Fuji even if I was 0.3s slower than the Vette (only did 5 laps). This will be the best car on twisty tracks, but struggle at Monza
The Vette is a great allrounder. Good on everything
The Masserati has great potential, but is a bit trickier to drive and a little slower than the Vette overall.
My BMW is not broken in and I cannot get full HP. Very similar pace as the Vette though, and I think these two cars are the best cars overall.
I sorted out the Jag setup a bit. I think its about the same as the Masserati in total. The Masserati corners a little better, but the Jag has faster straight line speed.
The Dodge is the slowest here. Its not a complete dog, but the other cars handles better. And bar the Camaro, the Dodge is the slowest in a straight line.
Overall, I don't think the rating of the cars are all that bad. I', going to take the challange and use the Dodge for the competition.