This model is very easy to build and very nice to play with for young kids. It is based on a main body (Power Functions 4.5V IR Receiver RC Car Base, part no: x1953cx1) that includes a motor (4.5 v) , a steering device, 3 pen light AA batteries and the PF IR receiver. You need to place a axle (10 long) at the rear before you can attach the wheels to the car base. Each Racer has a IR channel switch (on the bottum) and it is possible to use 4 different channels.
The IR controller (included in the set) can drive the car forward and backward. The car can do both left and right steering. The Power Functions IR controller has only one speed: full throttle forward or backward!
One big advantage of these IR controllers is that the speed can be adjust from slow to fast in 7 steps. But even with these PF IR controllers it is not possible to steer a bit more or less to a direction. It's either left, right or straight.
When I tried the LEGO racers I noticed that one of the cars couldn't drive in a straight line. It always made a slide turn left. The screw on the bottom side is used to adjust the steering device in order the let it drive straight forward.
In my video at Youtube I show how the LEGO Racer acts when it is controlled by the two different PF IR remote controls:
My LEGO projects 
