[Dayrion]

Return an integer :

PHP код:

GetPlayerSpeed(playerid)
{
    new
        Float:x,
        Float:y,
        Float:z;
    GetVehicleVelocity(GetPlayerVehicleID(playerid), x, y, z);
    return floatround(floatsqroot(floatpower(floatabs(x), 2.0) + floatpower(floatabs(y), 2.0) + floatpower(floatabs(z), 2.0)) * 195.28625);
} 


EDIT: There is not a REAL magic number since each (almost) vehicle are his own ratio.