My favorite activity in Gran Turismo is finding the shittiest car and then racing the fastest cars I can on the Nurburgring and then beating their asses because I know the track so well.
GT Sport lets you pick what class of car you race against, so I can set it to be very unfair pretty easily.
The slowest car class in the game includes the Mazda Miata, which, with very sticky tires, is able to pass McLarens and Ferraris with ease.