I did another test with my Prius, this time not as abusive as running it out of gas. This time I filled the tank to the filler cap drove to work and back 140 miles round trip then refilled it took 2.6 gallons to top it off, the Prius C computer said I was getting 53.8 MPG. I calculate about 53.8 MPG to me the computer is spot on Also my Prius C has 7,500+ miles
Did you refill it to the filler cap? I.e. you could see fuel on the initial fill and on the subsequent fill?
Nice. You will be better able to notice trends if you can get a bit more precision in the measurements. For example given the uncertainty as given, you could have gotten anywhere between 52.6 and 55.1. If you use the trip odometer you can get 1/10ths of a mile, and many gas pumps give 1/100ths, or even 1/1000ths of a gallon. Good luck.
you can seriously damage your EVAP system by overfilling, i.e. charcoal canister and would not be validated under warranty due to during insp would be seen flooded with fuel. (ive seen it done quite a few times). just a warning, you should only fill until shutoff(assuming that the amount that was filled is reasonable not just 2 gal).
Trust the gas pump. That pump costs almost as much as your car, but it only does one job. I try to use the same pump at the same station. If possible, I park the car in the same spot and direction so the fuel tank is not tilted differently. I insert the nozzle to the same depth and fill until the first shutoff. There will be some slight variation each time, but the variations will average out in the long run. A basic tenet of measurement science is with a single measurement the random variation may overwhelm the effect you are trying to measure. With multiple measurements the random variations cancel and true effects are additive. Averaging a couple dozen fill-ups will result in more precision than any single measurement. Tom
don't take it personal Tom, really I think its a compliment. If I took things said about me on here, I would never come back here. but its a forum, some people joke and have fun and others are downright mean, and that's what the ignore feature is all about. and sometimes the advice on these threads go way overboard, if you read your post like you didn't write it and you watch the Big Bang Theory what you wrote is exactly like what Sheldon Cooper would say, so sorry if I offended you. And the reason I called this thread "actual mileage My vary" wasn't a typo, I knew if I made it a general title, then people would assume they would get the same results, that's why I say My Vary. its my test on my car and I posted my findings
Over 5000+ miles and 17 refuelings, my indicated versus calculated figure has varied from spot-on to an over 3 mpg difference. Indicated mpg's have yet to be less than calculated. Different pumps at different stations, by the way.
Sorry...going back to the Sheldon comment (I haven't been on here in a while). I'm a college professor (Faculty of Science) and I hear the term used quite frequently- always as a term of endearment and somehow a suggestion of respect . (In fact, it has been directed at me a number of times.) Sorry that you were offended Tom. My natural first assumption is that since we all share a commonality in our appreciation of a fine automobile, there is seldom any subversive hostility or malice behind such comments. I like to assume that members generally have good intentions and we are united by a common bond. Peace, Love and Understanding...
