So close to highway rating
 

Today's fill yielded 23.978mpg. I know 24 is within reach for this 'around town' commute.

The pros: I can use 5th in one segment of my commute where previously 4th was used. I used neutral to traffic lights when coasting in gear would have caused too much engine braking. I'm getting better at shifting by ear.

The cons: A few lights were timed rather poorly. Construction zones made me lose a bit of momentum. This tank included some A/C and blower use. I know this summer will mean only more A/C use, but hopefully the warmer temps will cancel out that factor.

When I filled up, the number of gallons seemed unreal. I had to go to a second click to verify that I was truly on full. Had I not done that, this might have been a 24mpg tank.

I am hoping that the warm summer weather (less dense air, better start-up temps) will mean 24 is right around the corner.

Even so, today was a personal record if I set aside the highway roadtrips that I've logged and only count around town fills.

Over the course of just 3000 miles, 24mpg versus the 20mpg combined rating, will mean 25 gallons saved - or about $91 at the current national average price.

I think you are there. 24 I mean. something about significant figures, how accurate your fill is, and .022 mpg being pretty well inside the "noise" of .25 gallon fill errors, your odometer error, heck even fuel expansion.

...always "round" to integer numbers!

...hence, anything between 23.5 and 24.4 is 24!

Well, today sealed the deal pretty much. 24.8mpg on this fill.

The only variable was the fact that last tank fill I went to click #2 (see above story), so it's like I got a free 'bonus' amount of fuel but I know that wouldn't have given me an extra 8/10ths of an mpg.

I've also been filling much slower after having read the thread about fill speeds - maybe that's helping a little.


With the nicer weather, there are a lot of pedestrians, so I'm trying to be very conscious about not turning the engine on until it's clear. If I had passengers, I'm sure they'd be curious.

This tank, I learned that on flat terrain 5th is good for as low as 48mph or so. It can probably do 45, but it would require an extremely steady foot, and I don't want to chance lugging.

I am probably going to up my tire pressure from 33 to 35psi this weekend and see how it feels. No intent to approach max sidewall (44ppsi), just a little extra air.

My goal is to hit a very consistent 24 this summer without trying and wean myself almost completely off the speedometer. All by ear baby.

Congrats! Are you using instrumentation yet? I'm guessing no based on your "by ear" comment. I did the same for a bit, but saw HUGE gains once I got my MPGuino. Since your truck is new, get a SGII - it will pay itself off fast.
Read around here more on the pressure thing; most of us split the difference - the manufacturer tire psi is a minimum for safety. I fill to a bit above that on all our cars - sometimes you go a few weeks or a month without checking. Going from 38 psi to 32 is no big deal for FE or safety. Going from 33 to 27 is not as safe (although not awful) and WILL hurt FE.

A Scan Gauge is something that I've really thought about. I know that would answer a lot of my questions when there is more than one seemingly effective ways to do something (like a certain segment of my commute).

But I'm afraid that I will become too reliant on instrumentation, and my driving safety would suffer. That's my hold up.

Your take on tire pressure is interesting. So rolling resistance does not have a linear relationship with pressure, but more of a diminishing return?

That's right.
You can't keep cranking up the tyre pressure and hope to get big gains every time.
The biggest gain is when you increase tyre pressure from car manufacturer specifications (and in real life, often below) to say 10 psi above that value.
The results of doing so will be readily noticeable.

Always fill up the same way, or you're introducing even more variables.


I always insert the fuel nozzle so that the copper-ish part lines up with the side of the car, and don't add more fuel after it shuts off automatically.

http://www.mischacoster.com/wp-conte.../03/foto-3.jpg

I have Nokian WR tires on my Canyon. There is a very noticeable difference in rolling resistance between 37 and 47 PSI. I have not tried higher pressures.

The Canyon responds very nicely to DWL. Either a vacuum gauge or a Scangauge is necessary because the throttle plate does not have a consistent relationship to gas pedal position.

I find it possible to hold 5th gear down to about 22 MPH on a smooth, level road. It will even accelerate from that speed, although only at about 1 MPH per city block.

You're definitely right. It was kind of a weird fluke that day. My mileage was significantly better than usual, so I didn't trust the first click. I was wrong.

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JR, 22mph and no signs of lugging? That's impressive. What rpm is that? I can do 47mph at around 1500 rpm in 5th - any lower and it doesn't feel right.

I've been winging the DWL. Gain speed before the ascent, and bleed off speed by the peak. Naturally, it's not terribly specific.

Maybe I'd consider a vacuum gauge, but my safety hang-up is still there.

At least with diesels, first click method is useless, there is way too much foam and amount of foam varies from fillup to fillup, so only method that works somehow, but not 100% is to fill so that you slowly put last 2 gallons in and then fill up to neck, so that you can see level of fuel, this of course is then car related if it is possible to do so or not.

1 click method can have variance of 2 gallons in my car (diesel), so that is not always well working method.

22 MPH is about 700 RPM. At that speed, there is a shuddering due to the torque pulses but the engine appears to run smoothly. I do try to stay below about 10 lbs MAP (Manifold Absolute Pressure) at less than 1000 RPM because it runs smoother there. At 700 RPM, the voltage will drop to below 14 volts.

It is challenging to properly DWL the Canyon. The mapping from the gas pedal to the throttle plate is variable such that the MAP will change by several PSI with the gas pedal held dead still. I find that 90% of my driving is between 7 and 10 lbs MAP.

Safety is important. I only scan instruments when nobody is close. No close oncoming traffic, nobody in a position where they could pull out in front, nobody close in front who could stop quick, no tailgaters behind, no tight curves or hills with short sight distance, no obvious hazards, no deer standing by the road, etc. It takes practice.

Good work on meeting your goal!
 

I just thought I'd chime in since I am also approaching my milestone value. (30mpg)

I drove my 4-cylender '98 Rav4 by ear and did fairly well at 28 mpg in the winter and 32 mpg in the summer (although that number could have been improved on if I hadn't stripped out 5th gear). Having the manufacturer installed gauges in my Tribeca has helped me adjust my driving style from good to better. Now, with the 6-cylinder Tribeca, I'm hoping to eventually get the same mileage.

As a note on the tire pressure; the manufacturer lists 33psi and I run 38psi. I've tried to run higher but the TPMS lights up when the pressure exceeds 40psi. Starting cold at 38 I find that it doesn't warm up enough over my commute to exceed the 40psi threshold. I religiously check the tire pressure with every fill up. Fortunately my service station is one of the few left that offers free air, so an adjustment of 1-2psi in one tire doesn't put me out $.75 each time to run the compressor.

As a note on re-fueling; Definitely be as consistent as possible. I will go as far as filling up at the same time of day at the same pump at the same station whenever possible. Usually in the early morning when the station is less busy and the ambient temperature is cooler. I've always understood that their was a temperature expansion factor on the fuel but initially thought it was insignificant. That changed when I had to calculate that temperature-expansion coefficient as part of a chemical engineering homework assignment. Remember, your fuel is sold by volume not by mass (weight). I will admit, if your regular commute is short, the expansion factor doesn't really amount to much. However, when your driving over 25k miles per year, the higher cost of less dense fuel eventually adds up.

A note on significant figures; As other posters have noted, accuracy in measurement is vital for retaining significant figures. If there is variability (or "error") in your measurement it reduces the number of significant figures that you can report. At best, for my own uses, I can only justify reporting to one tenth (0.1) mpg and that's probably pushing it. As a side note, my manufacturer-installed computer will only resolve three tenths (0.3) mpg. (With a systematic calculation error of 0.7mpg above actual.)

Another useful tool is the fuel log in the "Garage" section on this site. It allows you to track your FE history. If you keep notes with it it will allow you to see trends. It also allows others to see how you're doing especially if you note the mods or causes for change in the comments sections.

Congratulations on hitting your goal. Now that you're there, do you have plans on improving on that number?

Nice. With 28 in the winter, I'm sure you'll hit 30.

My only goal now for now is to be able to hit 24 with less effort. I want to be more consistent.