Today's update introduces manual shifting. From the HOME screen, touch the gears then the slider icons.

Scroll down to Transmission and choose Manual. The default is Automatic.

Next, you will want to customize where the shift buttons appear on your screen when in a race. Go back one screen, then choose the device icon. I use Accelerometer but whichever mode you prefer, touch this option.

You will now see this screen.

Push OK, then move your buttons around to wherever you want them to appear in the game. You can pinch them to increase or decrease their size. Here is how I have them set up. For me, it makes more sense to be able to upshift with my left thumb since my right thumb is for the gas pedal. Then I downshift with my right thumb, while my left thumb is braking. To be accurate, you really SHOULD lift your right thumb off of the gas while your left thumb is downshifting since you would never push in a car's clutch to downshift while applying full gas. (Well if you want to burn up your engine then you would do this!)

Here is how it all looks in the game. (I race with bonnet view.)

Every race will begin in neutral so even before you are allowed to hit the gas, you will want to upshift into first while the clock is counting down to start.