Someone needs to fab up a Land Rover-esque "safari roof" or whatever it was called with their double-layer roof. Top roof takes the heat, gets cooled off as you drive. Bottom one doesn't get hot, so much less heat radiated into the cabin. No need for A/C then!

You want your car to warm up faster, make a grille block. Leave the heat off for the first few minutes so the engine warms faster.

 

Which is about right. What people on this forum don't seem to realize is that this is an "engine efficiency" gauge, not a fuel economy gauge. Once the power has left the engine, it is calculated. All drivetrain loss in power/economy is not calculated, which is why most MT guys are right around 10% and AT guys are between 15-20%.

 

First tank, brand-new car, mostly stop-and-go driving. Gauge: 35.3 mpg. Calculated: 33.2 mpg.

Not bad for a car that doesn't yet have 500 miles on it. About 10% better than I was getting with my '99 Civic EX 5mt.

 

Naphthalene moth balls as a fuel additive is an urban legend. They may have had some usefulness prior to the Korean war, or in 3rd world countries where gas quality is poor.

Naphthalene has a blending motor octane number of 90, so the addition of a significant amount of mothballs could increase the octane, and they were soluble in gasoline. The amount usually required to appreciably increase the octane also had some adverse effects. The most obvious was due to the high melting point ( 80C ). When the fuel evaporated the naphthalene would precipitate out, blocking jets and filters. With modern gasolines, naphthalene is more likely to reduce the octane rating and the amount required for low octane fuels will also create operational and emissions problems.

So, if you think you know more than a chemical engineer about blending motor fuels, and want to risk clogging up your injection system and incurring some expensive repair bills, go ahead.

 

I have the same issue with my base FIT AT. After the second tank of gas I decided to measure the accuracy of the dash reading. After 320 miles I did a fill up of 9.76 gallons. Dash indicated 37.3 MPG, but my calculations indicated 32.83. This is a pretty big difference. My first tank was 30.96. I did not have a dash reading because I kept resetting to see how high i could get it on some short trips.

 

I just subtract 5mpg from ours. It's a feel-good gauge. If Honda really cared, they'd help us use it as a real help to get the most from our cars.

 

I am not too concerned what the gauge is showing. I always record my gas purchases( Anal that way) and then can calculate over many tanks vs one where it may not be quite as full/less as the previous. I did do my last two tanks and got 45 and 43 mpg using Canadian gallons. So around 35-37 US. I am happy so not too concerned.

 

While the explanation that the gauge is reporting engine efficiency, rather than actual MPG because of drivetrain losses is appealing, the gauge is relying on software, and Honda could modify the software to generate an accurate estimate if they chose, so "feel-good" gauge sounds about right. On my first tank the gauge read 31.5 mpg, and I calculated exactly 30 mpg -- which was less of a discrepancy than I expected. The most useful purpose of the gauge is to educate your right foot.

 

Unless you use the same pump, you calculation will be off. Each pump shuts off at a different level.

You'll need more than one fill up to figure out Honda's error. The avg. is about 10%.

 

the alternator will provide the same load on the engine regardless of the load on it. electronics will not affect gas mileage.

posted by an mecp certified audio and electronics installer

 

I bought my Fit about 2 months ago and was getting on the computer a reading of 34 or 35 miles per gallon, I did the math on every tank and found that Fit was only getting 30 to 32 mpg, I started checking things to improve on that and found that the tires were under inflated, the front ones only had 28lbs and the rear ones 24lbs, I brought them up to 35lbs in front and 30lbs in rear and Fit has been consistently getting at least one more mpg on every tank. Honda must be saving a lot of money on every Fit they manufacture by underinflating their tires plus all the weight savings when they ship them from Japan to the US. LOL

 

That's incorrect. The alternator is not continually producing it's max output but is controlled by the voltage regulator based on the electrical load presented. Higher electrical load will cause a higher mechanical load/drag.

You can sometimes see the RPM's drop at idle when turning on high-power-consumption devices like the high beams as the alternator places more mechanical load on the engine to keep up with the electrical demand, not unlike the RPM drop when the AC compressor places a mechanical load on the engine.

 

If you don't use the automatic shut off as a rule and top it off by hand until you see gas at the mouth of the filler neck, you will get a more accurate reading on your gals used X miles traveled.

 

I did that too.
My first tank I calculated 32.7 mpg mostly city
Second tank was all highway, wife and I driving 65-75 mph...got 34.6mpg
Third tank was all highway, 4 people and 1 kid (maxed out) and got 31.mpg
Fourth tank was half in town short stops and half highway, same people and got 26.5 mpg.
What I found out by my 5th tank is that this motor doesn't have any torque, and I get the same dam mileage going 80 as I do 65 if there are 4 people inside. The less amount of weight I have, the slower I can go which reduces my rpm's and gives me better mpgs. I don't think I'll ever see the 40+ mpgs people talk about. Especially not with the AC on all the time (live in phoenix).

Don't civics get better mpg than this? Seems like if there was just 15-25 more horsepower, then these cars would do better on the highway.

I'm kind've disappointed, my father gets 36 mpg in his camry all the time!
I picked a much smaller car to blow his mpg's away

 

Just a hair over 43mpg average this last tank (calculated at the pump, not from the computer, which read 46.4 for this tank). Much more AC use this tank - more than half the tank was with the AC on, but not maxed - typically 1/3 of the way from full cold. I've used less than 30 gallons for my first 1200 miles....extremely happy with that.

dankstang, if your dad is getting 36mpg all the time in a Camry, and you're getting 30-31 in your Fit...your driving habits differ greatly from one another.

 

Driving habits do differ. Along with him hardly using ac even when its hot out, having lower interstate speeds and buying the best tires he can find for mpg's.

After reading posts from hypermilers, it looks like I need ti inflate my tires to the max reccommended psi for better mpgs.

Gotta love the instant economy guage, now its a game for mpgs not mph.

 

Well, this thread seems to keep going, so I'll go ahead and provide an update on what I got on that tank that started out quite well... Indicator: 42.9, measured: 38.9. Sure, just when I post a MPG report, does my next tank end up being noticeably better...

 

It's good to see that you acknowledge that the mileage difference is not really the fault of the car

The economy gauge definitely reads high on these cars, but within a couple of fillups actually calculating at the pump vs. what's on the economy gauge, you'll figure out what the margin of error is. What the economy gauge DOES do, which is great, is remind you to keep your foot out of it. Trust me, you ARE getting worse mileage at 80 than at 65.

But at least feel good in the knowledge that if you were driving like you are, doing 80, AC on all the time, 4 people in the car in a Camry....not only would you be having a lot less fun, but you'd be getting significantly worse mileage.

 

272 mi day trip, 142 mi back roads 45/50mph.130 mi interstate 60/62 no hurry.

5.521galllons/ 49.2 car has 19000 miles 2009 mt sport. a light foot will do it,
also have a scan gage .

 

quick trip this weekend. Drove 200 miles, almost all highway and cruise control, gauge said 40.5 mpg. spent 2 days driving in the city, did a 4 gallon refill and returned home for another 200 miles. Gauge read 38.5 mpg. manual calculation of 474 miles divided by 14 gallons = 33.85 mpg. Annoyed that the meter is off by a factor of 15-20%.