<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META http-equiv=Content-Type content="text/html; charset=iso-8859-1"> <STYLE>.hmmessage P { PADDING-RIGHT: 0px; PADDING-LEFT: 0px; PADDING-BOTTOM: 0px; MARGIN: 0px; PADDING-TOP: 0px } BODY.hmmessage { FONT-SIZE: 10pt; FONT-FAMILY: Tahoma } </STYLE> <META content="MSHTML 6.00.2900.3354" name=GENERATOR></HEAD> <BODY class=hmmessage bgColor=#ffffff> <DIV><FONT face=Arial size=3>I don't understand your logic at all Terry. The ONLY way to accurately calculate your fuel economy is to divide the miles driven by the gallons used - and you really need to do that over several tankfulls at least to negate the effects of filling the tank to different levels each time. Calculating the mileage with all fule purchases and miles driven over a couple years will give you an EXACT fuel mileage. Who only knows how accurate the MFD is.</FONT></DIV> <DIV><FONT face=Arial size=3></FONT> </DIV> <DIV><FONT face=Arial size=3>Terry Farrell</FONT></DIV> <BLOCKQUOTE style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px"> <DIV style="FONT: 10pt arial">----- Original Message ----- </DIV> <DIV style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><FONT size=3></FONT> </DIV>Calculating mpg on a prius by how much gas you put in the tank is no where near as accurate as the MFD calculation, since the prius uses a FLEXIBLE bladder that expands and contracts (sound familiar?) with temperature. This makes it impossible to know if your tank-which at most holds 11.9 US gallons-if full aftet fill up. WHen the filler nozzle shuts off automatically, DO NOT force more gas into the bladder as this can cause damage to the engine! So depending on where you live and how warm/cold it is, you may only get 7-8 gallons into the tank when the nozzle clicks off, telling you it's full! I live in warm temps so I can usually get close to a true full tank on fillup, but never let the indicator drop below two "pips". My best tank has averaged 66 mpg. <BR><BR>Terry Peterson<BR><BR>> I have a 2005 Prius. For three years, I have calculated the mileage on every drop of gas I have used. The 3-year overall average is 51.1 mpg. I have gotten 60 mpg on trips at 45 mph with few stops. I have gotten no less than 48 mpg driving 70 mph. The mileage display has averaged 1,4 better than the calculate mileage.<BR>> <BR>> Frank Emerson</BLOCKQUOTE></BODY></HTML>