[Bakr]

You will be using the bit-wise AND check. I would go into detail why, but it explains thoroughly on the wiki. Take a look at this page: https://sampwiki.blast.hk/wiki/OnPlayerKeyStateChange

Also, to check if the player clicked the right mouse button (which would be fire button), you can use the KEY_FIRE definition.

pawn Код:

public OnPlayerKeyStateChange(playerid, newkeys, oldkeys)
{    
   if (newkeys & KEY_FIRE)    
   {        
      new vehid = GetPlayerVehicleID(playerid);        
      if(IsPlayerInAnyVehicle(playerid))        
      {            
         if (turbo == 1)            
         {                
            new Float:Velocity[3];                
            GetVehicleVelocity(vehid, Velocity[0], Velocity[1], Velocity[2]);                
            if(Velocity[0] < maxspeed  && Velocity[1] < maxspeed && Velocity[0] > -maxspeed && Velocity[1] > -maxspeed)                
            {                    
               SetVehicleVelocity(vehid, Velocity[0]*speed, Velocity[1]*speed, 0.0);                
            }            
         }        
      }    
   }    
   return 1;
}