Won't the MFD's MPG consistently be undercalculated?

When one is coasting and going 99.9 mpg, isn't that because it can't go any higher than 99.9 mpg when if fact you could be going 110 mg or more? So if this is calculated in to your average mpg on the consumption screen, the computer is using 99.9 mpg and is actually underestimating correct?

Or is the way mpg being calculated just miles driving vs the amount of gas consumed since the last reset?

 

<div class='quotetop'>QUOTE(qbee42 @ Jun 25 2006, 02:01 PM) [snapback]276557[/snapback]</div>

Ah. Ok.

 

<div class='quotetop'>QUOTE(berylrb @ Jun 25 2006, 04:17 PM) [snapback]276596[/snapback]</div>

Thanks.