Detailed cars info
Reina's boss car is a ferrari testarossa, it's not as fast as reina's r, nor if it was "the best" car. But it is a ferrari, I'm gonna put some fair points on the handling just for that
Kei's father has history with some well known car tuners. The supra he drove is one of his dad greatest legacy. In akio's z era his car has improved later be known as the "monster machine". Now here's the thing tho... he can't really control his car, so what happen in the end the tuners(his dad's friends) tuned down kei's supra so it'll be a lot stable. In different terms, it is a lot slower but easier to handle now
Assuming that the supra is still in its "monster machine" prime, I'll say they have the same stats. Same speed and harder to handle