Custom 'Fuelly' signature

<?php
// Read template image into memory variable $im
$im = imagecreatefrompng("bike_template.png");

// Change $im to transparent background
imagesavealpha($im, true);

// 'Get' value from url ie: [url]http://files.forestcitynetwerxs.com/mileage.php?metric=3.381[/url]
$metric = htmlspecialchars($_GET["metric"]);


// Convert metric L/100 into miles per US gallon
if ($metric==0){
	$usgal = "0";
}else{
	$usgal = round(((100*3.785411784)/(1.609344*$metric)),1);
};

// Convert numbers to text rounded to nearest decimal point
$metric = sprintf("%3.1f", $metric);
$usgal = sprintf("%4.1f", $usgal);
	

$textcolor = imagecolorallocate($im, 255, 0, 0); // Set textcolor to red --> '255,0,0'
$mysize = 0;
$x = 163;
$y = 20;

// Add text to $im
// specify size, x and y coordinate, the actual text and the color
imagestring($im, $mysize+3, $x-1,  $y+0,  "L/100", $textcolor);
imagestring($im, $mysize+4, $x+10, $y+10, $metric, $textcolor);
imagestring($im, $mysize+3, $x+10, $y+26, "M",     $textcolor);
imagestring($im, $mysize+3, $x+19, $y+26, "P",     $textcolor);
imagestring($im, $mysize+3, $x+27, $y+26, "G",     $textcolor);
imagestring($im, $mysize+4, $x+2,  $y+36, $usgal,  $textcolor);

// Now that the image $im in memory has had the red text placed where I want it
// output the image 
header('Content-type: image/png');
imagepng($im);

// That being done clean up after yourself
imagedestroy($im);
?>