I was wondering if i could use one of those cheap as RC cars as a wireless remote connected to the arduino.
They have 4 channels, and i could just wire them up to the digital pins on the arduino.
Would that be possible?
Yes, it's possible, specially if you don't need very tight timing and you can afford to miss one refresh cycle.
In more details: Those hobby servos are controlled by a TTL-level PWM (or PPM) signal. What you call it doesn't really matter, each servo gets a signal of 0.5-1.5 ms length, refreshed every 20 ms. You can read the length of those signals with pulseIn() to retrieve the position of each servo giving you an analogue input.
The main challenge is to get to the signals. Some of the cheap toys don't expose all the received signals, but process some on the information directly. The channel for the motor control is a popular victim for this treatment. In those situations you'll have to do some reverse engineering to find the signals.
And by the way, most cars have only a 2-channel remote control: Left-Right on one channel and Speed on the other.
hey frien i suggest, better you buy a cheap rf module you can yet it easily. and you too g et high range .
talking about 4 channel RC cars contains 2 channel, they used simple transistor switchaing, as far as i knoe.