well... if you have a longer car that is flatter it will have lift which lowers speed or it will lift off the ground.
Like a long style car , in my opinion
Not as much as the shape of the car but different finishes do affect drag.
a cube
A small skinny car is best. you can even cut out peices of wood in the shape to make it lighter.
Bugatti chiron
viper
the blue
It is depended on the shape of the wheels to determine how much friction is applied.
Need For Speed : Hot Pursuit is recently the best car game.
MERCEDIES
the shape of the car is vital when designing because if you want a high speed car then it has to be aerodynamic this makes it easier for the air to go around the car and stops it from having drag drag is the force of the air that is pushing on a car if you want a fast car you need less drag
Honda civic
Nissan 240