Changing Tier

On the map screen, if you touch the screen and drag to the left or right you'll be to access other Tiers that you've unlocked. Remember that you can visit old Tiers to play any races you have missed. 

Daily Battles

These races change every day and will help you earn extra funds.  In these races you will be loaned the same car as your opponent, putting you on a level playing field.  

Regulation Races

Regulation Races are a great way of earning yourself some extra dough; they'll always be available and you can select different difficulties. When a Regulation Race is selected you'll be able to see the difficulty, race length and how hard it will be in your current car.

Select harder difficulties to earn even more money. Remember, though: when you start a new Tier, you'll have to participate in other races before unlocking the higher difficulties. 

Restriction Races 

These races will ask you to strip off certain parts of your car or force you to be under a certain power or weight. With the Restriction Race selected on your map screen, take a look at the bottom right corner (1). Here you can see the exact requirements for the race.

If your car does not match the restriction then try to take off the upgrades (see upgrades tutorial).

Still not working? It may be that you have exhausted all of your options with this car in Restriction Races, so try getting a new ride or taking a look at other vehicles in your Garage. Remember, you can always come back to these races, so don’t fret if you can’t afford a new car.

Sometimes cars will need to be AWD,FWD,or RWD. Check out the link below for a breakdown of each car's drive type: 

Car drive types : CSR Racing

Mechanic 

Every now and then you may need a little help to ensure that you are the first to the finish line. The Mechanic (2) will give you a performance boost in exchange for some Gold.