Just filled my car up for the first time. $28 instead of the $40+ I'd been paying with my Bonneville.

My computed milage for the trip was 49.8 but the actual gallons/miles = 43.0. I know there have been threads about the bladder in the gas tank and the click point of the pump affecting the milage. But a 6.8 mpg difference? That seems extreme.

Of course, it's possible that the dealer didn't actually give me a full tank of gas. However, the indicator had all 10 bars.

I put the tank in the milage log. Is it better to put the computed MPG figure in or the actual gallons and miles? Does the calculator add up all the miles and all the gallons over time? Or does it just average the MPG figures?

David

Also, my signature doesn't reflect the tank I just put in. Is there a lag?

 

I'd chalk up the difference to not knowing exactly how full the tank was. Was the trip odometer on the MFD at 0 when you got the car? The dealer might have reset that, so the 49.8 could be closer to what you actually drove. Do you remember how many miles you drove before the first pip disappeared? The first pip tends to stick around longer than the other ones. You could see a "full" tank of gas even though you're down a gallon & a half.

On this site, I use the MFD mileage. I keep my hand calculations on another site (see my sig). It's really up to you.

It will average itself out over time. If you can, try to fill up at the same station & pump every time. At the station near my home the pumps are on a slight slant, so one pump will put more gas in and the other less.

There's a delay with the sig updating. It's updated by now.

Congrats on your first tank, too. Nice numbers no matter how you look at it. Just wait until it's broken in!!

 

You can NEVER trust the first tank. I find my '04 MFD is about 2% generous (about 1 MPG) vs actual miles and gallons put in over time. Tank to tank it can vary depending on how much you decide to 'round up' at the pump.
The low point on my lifetime ACTUAL was just under 42 MPG. 5 months, 16 fills, 5082 miles ~121.5 gallons. Starting your lifetime MPG calcs with WINTER weather isn't so fun . The lifetime rose to 46 at almost the 1 year point, weather started getting cooler and the numbers started falling again. Obviously I should stay home from Oct through Feb! Actually, last winter was a lot warmer than the first winter and my lifetime only dropped to 45 by the end of February.

Remember that you can not calculate your lifetime average by averaging the MFD averages. They do not take miles into account. You either need to use actual miles and gallons, or weight the MFD average by the # of miles on that tank for every reading.

 

I too entered my first tank, with a large discepancy from the display versus hand calc (43.5 vs 38.6). It's hard for me to accept, because my car was right off the truck. 1 mile on the OD when I took delivery. Yes, the dealer may not have topped it off, but to make the #'s work they would have had to short me 1.1 US gal. That also seems impractical because I drove a good 100 miles before I lost my first tick on the fuel indicator. Had they shorted me 1.1 gallons and I drove 2+ gallons, there is no way the fuel indicator would have still shown full more than 3 gallons down.

I am chalking it up to a combination of all things - break in/unknown starting quantity, etc.

By the way, I am not disappointed at being 15th from the bottom of the list with 38.6 mpg. I did extensive reading on how to P&G before buying, and my average across that tank was 50 mpg. The problem was my wife, who put 200 miles on it while I was away and told me "I think it has good pickup. Every time I asked for power it responded." She also has no concept of pulse, glide, regen or anything else hybrid related. So, all in all, 38.6 is not bad for a first rating.

 

My first tank with the dealer fillup was 43 mpg. My 2nd was 54 mpg, and the 3rd 55 mpg.

I usually go about 120 miles before the first tick disappears.

I threw out the first tank assuming that the dealer shorted me.

 

I ignored the first fillup because I also had no idea when they filled it versus the mileage recorded. I just did my second fill up today. I let the pump click off and I don't try to force anymore in. I assume with the bladder there will be some discrepancy with each fill. I am keeping a log book and will average it out over time. I was fortunate in that my calculations came out to 49.6 MPG. The computer had 50.5 MPG. Close enough for me.