Hi Winrya....see my thread on economy...I recently uncovered (today actually) that if i drive with the ac off, heated seats off and the 1000W subwoofer in the boot off my economy on a the same journey returns 27.5-29.5....
Dont ask me to explain it, but the toys will be used sparingly from now on.
I havent been on a long motorway drive yet, but plan to very soon to check out how much it improves.