4 speed VS Automatic

The four speed has the potential to go faster with the same set up, it weighs less and has less parasitic drivetrain loss. So, if everything else is the same, the 4 speed car will put more power to the ground.

But usually racing is more about consistency than the absolute fastest time, so the auto usually wins out. Perfect run to perfect run, the 4 speed will win. But unless you're VERY consistent with rowing your gears and have a skilled driver that knows how to control the clutch and gearbox to hook the car and make use of that extra power the auto will win more races.