I am trying to make Arduino uno to act as a keyboard, i have successfully flashed the USB-HID firmware in it using this link also and programmed it like this.

uint8_t buf[8] = {
 0
};

int inpin1 = 7; 
int inpin2 = 8;
int val1 = 0;
int val2 = 0;

void setup()
{
  Serial.begin(9600);
  delay(200);
  pinMode(inpin1, INPUT);
  pinMode(inpin2, INPUT);
}

void loop() 
{
  val1 = digitalRead(inpin1);
  if(val1 != HIGH)
 {
   buf[2] = 80; // Left Arrow
   Serial.write(buf, 8);
   releaseKey();
 }

val2 = digitalRead(inpin2);
if(val2 != HIGH)
{
   buf[2] = 79; // Right Arrow
   Serial.write(buf, 8);
   releaseKey();
}

 }

void releaseKey()
{
  buf[0] = 0;
  buf[2] = 0;
  Serial.write(buf, 8);
 }  

The above code works fine but the problem is that, when i tried to play a game which uses right arrow and left arrow and to control car i was using the push button which i connected to arduino as left and right arrow keys. But suppose if i want to turn a car. I have to press the key and then release the key to move it a very little to the right or left. So, if i want to turn the car either left or right, i have to press and release so many times that it becomes impossible to play the game. Do you anyone know how to resolve this problem.