I stopped this summer a couple of weeks after we returned from our 3-week road trip. Must have been just after I reached 13,000 miles. Just decided it was time to obsess over something new.
Recording gallons, price and odo reading provide the information I post in my Excel worksheet which calculates cost per mile (currently 5.1¢/mile over the last year averaged) as well as per tank. I might add, the "Consumption" screens MPG is within about ~3-4% of the calculated number. Compulsive? - Interested? - maybe...
Exactly why I'm keeping track! Couldn't have said it any better. I grow weary of the # of times people have 'claimed' 30 plus MPG on their 15 year old pick up trucks with NO data to back it up. Seriously, there are a lot of liars out there, just fooling themselves. And all it would take is a simple notepad to jot down the numbers when re-fueling, which is every week for most. The truth would really knock them down. When I do fill up (every 2 1/2 weeks or so), invaribly some one asks about the car and lies to me about their MPG. I just show them the display and they saunter off, paying their $50 every week. So much denial... There's always a justification to drive a sub-20 MPG vehicle, I've heard lots of reasons. Best ones are, "well, it gets 25 on the highway, downhill, with a tailwind, that's good enough".
I have always had a mileage book in all my cars, this is the first one I haven't had. Toyota will mark oil changes and tire rotation, so I gave it up, to the great relief of my family. I had one car that we had a book with three generations keeping track, my grandfather, father and me. I feel a bit sorry to have quit.
I started loggin data in 1983 with my '77 old cutlass. I continued when I moved to an Isuzu Impulse in 1984 and then to a Saturn Wagon in 1995. I sold the Saturn and continued with my 2004 Prius. I have a spreadsheet that shows every tank I've bought for the past 22 years. The Saturn data is still on the web at http://enerjazz.com/saturn/mileage.html. The Prius is on the web at: http://enerjazz.com/prius
I always kept a logbook in mycars' glove compartments and wrote in date, location of gas station, gals, cost, and then calculated the mileage. My dad was a mechanic and taught me to do that, in order to track how the engine was performing. Got married to an engineer in March '05. We bought Foxy in August to replace my old Civic. I put a new black leather bound journal in Foxy's glove box and made the initial entry. Then my husband took over the car for his work commute and I began driving his Accord. He never listed his gas fill-ups in the journal. Dan doesn't even remember the mileage of the Accord's last oil change! So much for the fabled engineer's rabid need for record keeping.
I never kept these kinds of records before I bought my Prius. I sure wish I had. I know that I would have been very disappointed with the mileage I got. I found this site about two weeks after I took delivery, and luckily I had the fuel receipts. I found an Excel spread sheet here and I have been maintaining it ever since. I know every cent I have put into this car. And I will be able to tell you when it pays itself off too. I have already identified that I save more than $100.00 a month on fuel alone.
I have always tracked distance and fuel economy in every vehicle I owned, VW Bugs, VW 411, VW diesel pickup, Toyota 4Runner (200k mi) and now the Prius. Having a current print-out handy is critical for understanding the health and well being of the Prius as well as answering inquiries of the curious. I voted this morning at 0700 and several people waiting to vote wanted to know about "that electric car." Having a spreadsheet of fuel economy for 15k mi provides solid evidence for the quality of owning a Prius.