Mine

#include <a_samp>

#define MAX_STRING 256

enum SavePlayerPosEnum
{
    Float:LastX,
    Float:LastY,
    Float:LastZ
}

new Text:Speedometer[MAX_PLAYERS];

new SavePlayerPos[MAX_PLAYERS][SavePlayerPosEnum];

forward Speed();

main()
{
        print("\n----------------------------------");
        print("  WG's Sexy Speedometer maybe has been loaded.");
        print("----------------------------------\n");
}

public OnFilterScriptInit( )
{
SetTimer("Speed", 500, true);
}

public OnPlayerExitVehicle(playerid, vehicleid)
{
if(IsPlayerConnected(playerid)) {

TextDrawHideForPlayer(playerid, Speedometer[playerid]);

}
return true;
}

public Speed()
{
  new string[MAX_STRING];
  for(new i=0;i<MAX_PLAYERS;i++)
   {
      if(IsPlayerConnected(i) && IsPlayerInAnyVehicle(i))
       {
	        TextDrawDestroy(Speedometer[i]);
	        new Float:x,Float:y,Float:z;
            new Float:distance,value;
            GetPlayerPos(i, x, y, z);
            distance = floatsqroot(floatpower(floatabs(floatsub(x,SavePlayerPos[i][LastX])),2)+floatpower(floatabs(floatsub(y,SavePlayerPos[i][LastY])),2)+floatpower(floatabs(floatsub(z,SavePlayerPos[i][LastZ])),2));
            value = floatround(distance * 11000);
            format(string, sizeof(string), "~b~KpH: ~g~%d",floatround(value/1400));
            Speedometer[i] = TextDrawCreate(90.0, 320.0, string);
            TextDrawTextSize(Speedometer[i], 60, 100);
            TextDrawUseBox(Speedometer[i], 1);
            TextDrawBoxColor(Speedometer[i], 0x000000FF);
            TextDrawSetOutline(Speedometer[i], 0);
            TextDrawFont(Speedometer[i], 3);
            TextDrawSetProportional(Speedometer[i], 1);
            TextDrawAlignment(Speedometer[i], 2);
            TextDrawShowForPlayer(i, Speedometer[i]);
            SavePlayerPos[i][LastX] = x;
            SavePlayerPos[i][LastY] = y;
            SavePlayerPos[i][LastZ] = z;
	   }
   }
  return true;
}