If you are in the vertical Portrait view you can find the Street Racers Services right under the teal highlighted Daily Unlock and above PlayMesh. Once in here you will begin at the Street Racers 3D Hospital, which will just include the line "You don't need the mechanic" if you are at full health. If you are not, then the Street Racers 3D Hospital will include a Heal button with a price above it. This will then heal you fully, and the cost of using the Street Racers 3D Hospital is directly correlated to how low in health you are and what your position in the game is like.
You will notice in the Street Racers 3D Hospital that your Bank Balance from the Street Racers 3D Bank is at the top of the screen. This is because the Street Racers 3D Hospital bill has to be paid from your Street Racers 3D Bank account. If you hit the Bank button at the bottom of the Street Racers 3D Services interface you will be taken there.
The Street Racers Bank consists of a text prompt that you can enter a dollar amount in and then several buttons that will control that amount. There are buttons for depositing and withdrawing, so you can just select the one that is appropriate for your purpose. All deposits will have a ten percent fee taken out of them, while withdrawals from your Street Racers 3D Bank account are free.