HEHHEHEHHE!!! si lo posto:

form2.php

<form method="POST" action="pagina.php">
<select name="data">
<?
//il codice per la connessione...
$sql = "SELECT id, carburante FROM alimentazione" ;
$result = mysql_query ( $sql );
while ( $row = mysql_fetch_array( $result ))
{
$id = $row['id'];
$carburante=$row['carburante'];
echo "<option value=>$carburante</option>";
}

?>
</select>
<input type="submit" name="submit" value="invia">
</form>

________________________________________________
PAGINA.php

<?php
//il codice per la connessione...
$carburante = $_POST['carburante'];
echo $carburante; //output del selected

?>