One of the biggest benefits of not using cruise control is that you can quickly make changes based upon the terrain. If you say the hypermiler has to mimic the cruise control, there often will not be many benefits. One exception would be if there are steep enough hills to maintain speed going down in an FAS.

 

I don't fully understand it either. A compromise might be to add an extra gallon in after the first click. That will still leave nearly a gallon of volume until the filler neck level. Also, if you are doing this at the beginning of your commute, your drive will lower the level some more.

The best way to handle occasional topoffs in your mileage calculations is to carry over the topped off volume of gas to the next tank. (Always base your tank on first click to first click.)

 

A few things here, so apologies for length. . .

Top-off. First, the top-off on mine is consistently, no matter the pump (and I've fueled the car in 8 states now), 1.8 gallons from first click-off to fuel visible in the fill inlet. Because I don't live in a state with those cursed emission-control sucker-nozzles, top-off is easy. The sucker-nozzle (sorry I don't know the official name for this, the one you find all over California and in some other major urban areas) makes topping difficult because it can actually suck excess gas back up the fill line into the pump without you knowing/realizing it. But given how full I fill mine, we can safely discount the other standard reason given for not topping off, that you might have fuel overflow into your evap cannister. (If that did happen, you'd get a check-engine light/code referring to a problem with the evap cannister.)

Tank capacity. Because I always fill to visible fuel in the filler inlet, I never have any question whether I'm replacing all that gas I use, so I'm confident about my refill figures. The most I've ever put in the tank was 12.6 gallons. I don't doubt for a minute Honda's claim of a 13.2 usable-gallon tank. Chances are it's more like 13.5, particularly if you've topped off to the filler inlet.

Running the tank dry. I wouldn't run the tank to empty repeatedly or frequently, but you don't need to worry about running it out once or twice -- carmakers expect people to be dolts about this, so they build systems that tolerate the occasional oops. I'm sure repeatedly running it to empty would, as people say, affect longevity of the fuel pump by having it run hotter than it would submerged. (But don't believe people too far: if the gasoline in the tank really cooled the pump *that* much, your gas would heat up too much to be safe/usable.) And I know that emptying the tank is always said to send all the gunk at the bottom of the tank into the fuel pickup/filter, but I've never seen evidence that this *actually* happens (as opposed to *can* happen -- as anything theoretically can). The four 1990-and-later cars I've had have gone between 140,000 and 150,000 miles without fuel filter changes, and I drive them down to E all the time. Ran one out once. Not a problem. (I'm skeptical about how much gunk is in there anyway. Are we buying dirty gas? Are our plastic tanks somehow flaking away? How are fuel filters lasting well over 100,000 miles if there's so much gunk available to clog them up?)

The one thing is, at the first hint of a stumble as you run out of gas, SHUT THE CAR OFF. At that point, there is still fuel in the line, it's just mixed with air bubbles that are causing the stumbling. It's still possible to restart the car without much cranking. If you run it until it doesn't even stumble anymore, it'll be very hard to restart.

How far on no bars. The problem with trying to say reliably how far you can go beyond the fuel light and no bars is that you can no longer reason on the basis of *averages* with so little gas. When the fuel light comes on, you've got about 1.4 gallons of gas left. (No matter, obviously, whether you topped off or not.) Depending on terrain and conditions, my FE average can be anywhere from 30 to 70. And it could be less than 30 in extremely bad conditions. So you just really have to know not what you've averaged but what you're *actually getting* when you hit that last gallon.

The tank I used 12.6 gallons, I ran out of bars just before the top of a mountain pass that I needed to coast down (20 miles) into town to gas. I sweated it some, but it was easy to max the mileage down the pass and drive gently the remaining miles to the gas station. So I ran about 20 miles on no bars and still had .6 gal left, but that was because I was well over my normal mileage for the last gallon.

Obviously you can't argue that one experience is representative. Everything in this post isn't a claim about how it *usually* works, but about how it *can* work, since it's worked that way for me. Apologies again for length.

--Doug

 

Nice job, peoples! Not sure if I can catch you, kenny. Just not willing to drive 48 on the Garden State Parkway

I was proud to hit my first 710-mi tank last week, with a record 61mpg tank!! ANd only filled up slightly under 12 gallons to do it, so no real risk of running dry, in spite of going ~50-mi past no bars.

The car simply amazes me, and stupefies my friends when I say it can get 60.4 mpg over a 700 mile tank. Or perhaps it would be better to boast that I am achieving those numbers (with a little help from my silver buddy)

So keep on rocking folks! The more you work it, that harder poor schlubs like me try to keep up!

 

Great numbers, Keith! How do you do it? H

 

Hey Harold,

I've mostly been going with the core advice seen around here, and CleanMPG.com. Ya know, tires at ~40psi, keeping the speed <55 when feasible, avoiding hard accel, anticipating lights / heavy traffic in order to keep rolling at reasonable speeds, minimize braking, avoid short trips, etc. Oh, and most importantly, not letting my girlfriend borrow her

Much like laurie and kenny, I had a great start after a fill-up a couple of weeks ago, so I just got competitive and pushed it for the rest of the tank. Ain't yet fixin' ta catch up to Kenny and the lead pack, though!

 

Do you stop pumping gas after the pump first shuts off?
Or do you squeeze the handle and pump more?

 

The regular Civic has a 13.2 gallon tank. But the Civic Hybrid only has a 12.3 gallon capacity. I believe this is because of the extra space the batteries require.

Anyway, it's possible to pump in more gasoline than the advertised tank capacity because the filler neck holds 1/2 gal. or so. Not recommended, but possible. I never fill my tank and tube completely, but I go to the third click.

Also, I've found that the Hybrid has one full gallon left after the fuel guage goes completely dark. My most recent fill-up took 11.3 gal. to the 3rd click, and I was 20 miles past "Empty." So the dreaded 'unkown zone' should get you at least as far as the current mpg avg. on your trip meter.

 

I thought the reason the hybird's tank was smaller is because it is not a tank but a bladder.

I think this is how it achieves zero evaporative emissions.
As gas expands and contracts with temp the bladder is free to do so without any fumes escaping.

 

I'm pretty sure the Prius is the only hybrid with a bladder style fuel tank.