[Sugarbug]

I'm 90% highway. Unlike 80% of the sheep on the highway, I use cruise control religiously. This prevents me from being the tard that passes me, falls back, passes me, falls back, passes me... need I go on?

It also /should/ keep my mileage more consistent. I have noticed, though, that the mileage gauge likes sit at 35 then drop to 30, then back to 35 off and on as I drive with no change in grade/distance to car in front of me. After a while it evens out and I normally see 35mpg for my 34 mile commute (90+% highway) with cruise control set at 75ish.

Any idea what's going on?

 

[TH23]

Since the gauge displays bars and not exact numbers, it's probably teetering between the two notches on the gauge because your instant mileage is fluctuating between say 33, 34, 35, 36, etc. It doesn't take much to cause such a change while cruising, even if you're steady on the throttle (or cruise control is steady on the throttle, whichever case it may be).

 

[Sugarbug]

Alright. Just wanted to be sure it wasn't a clue about dirty injectors or a bad pump. Thank you.

 

[TH23]

I'm sure your car is fine. Mine does the same thing when I'm cruising at a steady speed. I guess the only way to get a precise measurement of your instant mileage would be to get a Scan Gauge or Ultra Gauge and calibrate it to your car. I have a feeling that VCM may play tricks on a Scan Gauge, and you may not get a true reading that way, either. I have an Ultra Gauge that I still need to calibrate to this car, so I'll try to test that theory in the future once I burn through a few more tanks

 

[Username]

It probably is an indication of grade. Might be too slight to feel, but the engine can tell.

 

[HondaTechAV6]

yes, it's a clue about dirty injectors.

 

[newtohonda]

Rule of thumb is a 1% change in grade requires a 10% difference in power. So even subtle grade changes can radically alter the real time fuel use to maintain speed.

 

[HRollerman]

Alright. Just wanted to be sure it wasn't a clue about dirty injectors or a bad pump. Thank you.

Even though you aren't on a grade, the car still needs to apply throttle to maintain speed (with cruise on). When it throttles up your mileage bar drops as it is measuring gas mileage in as close to real time as can be measured & relayed.

We all have our theories on dirty injectors/direct inject issues. When my throttle response feels sluggish to me, I inevitably end up giving her an Italian tuneup. My logic being that mashing the gas every once in awhile would exacerbate any potential injector/pump issue and I'd rather have those issues pop up when the car is under full warranty.

 

[berrnard]

mine does that too, i also try to use CC all the time.


but i have noticed, with this car at least, if i dont use CC, i get better mpg. according to the computer.
on a hwy trip as much as 2-2.5mpg. again, according to the computer

 

[CobraPA]

Cruise control with Econ? Because if not, the cruise control is pretty aggressive on inclines. You won't get better gas mileage that way.

 

[Sugarbug]

Cruise control with Econ? Because if not, the cruise control is pretty aggressive on inclines. You won't get better gas mileage that way.

Yeah. Econ is pretty much always on. Very few inclines around the greater NOLA area.

mine does that too, i also try to use CC all the time.


but i have noticed, with this car at least, if i dont use CC, i get better mpg. according to the computer.
on a hwy trip as much as 2-2.5mpg. again, according to the computer

That's interesting. I'll have to try.

 

[desertrat]

I agree that it is perfectly normal and expected that the instantaneous mileage should vary all over the place when you drive, cruise control off or on. This is true of any vehicle, it is reacting to difference in grade, wind, and other factors that are undetectable to us. You may or may not get better mileage with the cruise control on, people who really pay close attention (not me) to mileage can usually beat the cruise control. I think the ECON mode is a good idea, as mentioned above CC is pretty aggressive when it changes speed with ECON off.

Some important factors for mileage are:
1. what you drive, lighter weight, less drag, and smaller engines work best
2. how you drive it, use the brakes as little as possible, stay out of traffic when you can
3. tire pressure, for mileage higher is better due to less rolling resistance

 

[Metal Metalic]

Also the type of fuel... 3 years ago we did not have a 10% Ethanol mix in the summer in our location. Now that is all we have. So now we have 32MPG when we had 34MPG for the first year of owning the VCM coupe.

 

[2-DoorAccord]

Also the type of fuel... 3 years ago we did not have a 10% Ethanol mix in the summer in our location. Now that is all we have. So now we have 32MPG when we had 34MPG for the first year of owning the VCM coupe.

Do a google search "I hate ethanol" and you will find many posts from me.

In light traffic I find myself thumbing the CC up and down 5-7 mph just to stretch the mpgs.

Try this if no one is behind. With the cruise set above 55 mph and the econ button on. After a stop, take the accord above 26 mph and hit the resume button. Wait,,wait,,wait & wait after 20 seconds you might be up to 55 mph. Econ does save gas.

Did I mention "I hate ethanol" ?
Lucky for us we have a non-ethanol station beside our (1.5 miles) and 2 miles from work.

Most fuel sources close to a marina are "Non-Ethanol".