new Speedlimit[MAX_PLAYERS];

CMD:speedlimit(playerid, params[])
{
	new string[128], speed;
	if(sscanf(params, "i", speed)) return SendClientMessage(playerid, COLOR_WHITE, "USAGE: /speedlimit [Max MPH]");
	if(speed < 0) return SendClientMessage(playerid, COLOR_GREY, "Invalid MPH speed.");
	Speedlimit[playerid] = speed;
	if(speed == 0) format(string, sizeof(string), " You have turned your speed limit off.", speed);
        else format(string, sizeof(string), " You have set your speed limit to %d MPH, any vehicle you drive will not go past this limit.", speed);
        SendClientMessage(playerid, COLOR_LIGHTBLUE, string);
	return 1;
}

// Speedlimit
		if(GetPlayerState(playerid) == PLAYER_STATE_DRIVER && Speedlimit[playerid])
		{
		    new a, b, c;
			GetPlayerKeys(playerid, a, b ,c);
		    if(a == 8 && GetVehicleSpeed(GetPlayerVehicleID(playerid), 0) > Speedlimit[playerid])
		    {
		        new newspeed = GetVehicleSpeed(GetPlayerVehicleID(playerid), 0) - Speedlimit[playerid];
		    	ModifyVehicleSpeed(GetPlayerVehicleID(playerid), -newspeed);
		    }
		}

Speedlimit[playerid] = 0;