Launching in Live Races isn't as easy as keeping the launch indicator lights green and the car doing the rest - you'll notice a Launch button on the left when you're sitting on the start line.
Now, in order to start your car, not only will you have to keep your launch indicator in the green, but you'll have to hit the launch button at the right moment too - hit it too late, and you'll waste valuable time; hit it too early, and you'll launch on time, but the wheel-spin will kill your acceleration off the line.
Lightly feather the pedal on the right hand side, making sure you keep your starting lights in the green at the moment the timer hits go.
In multiplayer, you'll also be required to tap a launch button when the timer hits go. Hit it too early and your wheels will spin, losing vital traction as you accelerate off the line; hit it too late and your opponent will get the jump on you!