No, it won't. Throttle plate has the same tendency to restrict air flow as the air filter. Unless you're talking about WOT, but then fuel efficiency isn't an issue.

Here's an interesting discussion of the topic over on the engineering tips forum.

Here's a study by the Oak Ridge boys.

 

Had the panel, and noticed some smoothness up top.

Replaced that with Typhoon and noticed more power overall. Pretty loud though.

 

The first link is a discussion in 2008 so it is all out of date, so you can actually ignore half of the argument.
Note that the Oak Ridge study *finally* completed in 2009 to put the issue to rest
Before then, If you actually try to follow anyone's claim for fuel saving references you see that it all came to be based on only 1993 or older DoE Oak Ridge studies based on carbureted cars.

In approximately like 2008 the DoE/fueleconomy.gov put up something to the effect of "new tests in progress" and finally when they completed their study, the new recommendations are up. But the cat is already out of the bag, and the statement "according to the Government save 10% by changing your filter" still floats around.

I think now after almost 3years the new report is finally starting to overtake the old idea. Notably, all the air filter manufacturers removed the "saves you gas/fuel economy" benefit from their marketing.

So perhaps this also goes to show that the status quo doesn't always stay the same. Don't be quick to accept crackpot ideas like hydrogen gas/browns gas generators, but keep an open mind and don't dismiss new ideas outright either.

 

On which part. A engine is a air pump and taking away restriction will raise the VE. A engine will get the air it needs either way even with the so called clog air filter, but I dont recommend the clogged filter. Air will find its way past the air box and it will be unfiltered air or through blown gaskets or oil seals. Also fuel has oxygen in it and it will use more of it to produce the power needed.

 

Ahhh, so closing the throttle will blow the gaskets.

Remember this: to preserve engine integrity, better to floor it all the time.

 

A Fit is not the best example of how improving intake and exhaust efficiency improve mileage. It is fairly optimized from the factory. That's not to say gains aren't possible, just that they are hard to achieve.

More extreme applications show just how important it is to make it easy for an engine to do it's job. My uncles 454 gas powered motorhome went from 8mpg to 11mpg with a full Banks intake, headers, exhaust kit and that is the norm in the motorhome world. His motorhome is only used at one speed in one way...interstate cruising at 65...so the gains are real. My diesel Superduty went from 17mpg to 21mpg with intake and turbo back exhaust.

Any vehicle requires x amount of whp to maintain x speed. Decreasing the VE of a given engine will mean that it has to work harder to produce that x amount of whp and the opposite is also true. Working harder means either more fuel or more rpm which in turn means more fuel used.

 

Gains in power may be achieved, although without hanging a blower on it I doubt you could measure the difference in air filters/intakes/exhausts on the Fit.

None of these will increase MPG if the engine runs efficiently, as it was designed to do.

Try reading the links I posted.

The simple reality is the engine is controlled by a throttle plate that opens and closes. The air filter in front of the throttle body merely enhances the throttle's action. It doesn't change power magically at any given rate of air flow. A severely clogged filter (to the extent of being pulled from its frame) does not alter MPG a bit. It may even help slightly by reducing available power.

 

Gas Mileage Tips - Keeping Your Vehicle in Shape

I disagree that a clogged filter in a fuel injection car gets better mpg. It gets the air it needs from unfiltered air weather its the rubber tube or vacuum leak. A better running car always gets better mpg.

 

Did you even bother to read your own link?

Quote:

NEW INFORMATION: Replacing a Clogged Air Filter on Modern Cars Improves Performance but Not MPG

The study they quote shows improved MPG in some tests with a severely clogged filter. The study's conclusion is the difference isn't significant.

If it got "the air it needs from unfiltered air weather[sic] its the rubber tube or vacuum leak" all our cars would be sucking unfiltered air at idle. What do you think the throttle does?

 

I read all of the posts and saw no useful information. I am fully aware of how a modern motor operates. The HUGE thing you are failing to realize is that restrictions placed in front of the throttle body reduce the amount of air that passes through it at any given throttle position. The ecu receives information from the throttle position sensor and mass air flow sensor to determine the amount of fuel to use. To make sure that it is using the correct fuel tables it constantly monitors the O2 sensor for the correct A/F ratio within a range.

What I found with the last modern car that spent hours on a chassis dyno was that improvements in intake and exhaust flow resulted in the car running on the lean side of the chosen fuel map. This sometimes required several cycles of the ecu to learn the new flow, but it always resulted in a slightly leaner a/f ratio.

The leaner a car runs the better the fuel efficiency.

You can spend the rest of your life looking at other peoples research or do your own. I have modified countless vehicles as have family members and friends and been around cars my entire 39 years on this planet and I'm reporting what I have found to be true.

 

I have two major problems with the Oakridge test (yes, I read the stupid thing). 1. They said that the AFR was the same regardless. Go to any local speed shop with a chassis dyno and ask them what they see everyday on almost every car. They will tell you that intake and exhaust improvements result in a leaner AFR even in the most modern cars. 2. I did not see any mention of letting the ecu spend enough time to learn the new airflow. As people who have seen a mpg increase from the use of premium fuel will attest to, it takes several tanks of premium before the ecu settles on a table with more aggressive timing to see any gains.

 

I have to add that I am speaking in generalities. The Fit may already be optimized from the factory. I don't know because I have not improved the intake or exhaust flow on ours and charted the fuel mileage difference. I just know that I have seen improvements on other modern cars.

 

The K&N in box air filters are a good choice for our Honda Fit.I have one on my Honda Fit and love it!!!Sound,MPG and more HP are not a big issue for me.I like it because you can use it over and over when you clean it.....

 

Now that's a good, day to day, real life simple answer... connected to the OP.

 

Ditto. I got way off on a tangent. Buy the K&N, stick it in, and enjoy not having to service or buy another filter for a long time.

 

Just don't over oil it.

 

LOL...on that we can agree

 

There is a difference between clogged and dirty air cleaner. So pick one. A clogged air filter will cause engine problems. The throttle body can be open as much as need even if there is no foot on the pedal. Its electronic so when you think its closed it can open as much as 30 percent. You also dont take into account regular gas has 10 percent ethanol or more. So it will add the O2 needed by adding more fuel which will strain the emission system too.

I had my air filter in my Fit for 36000 miles, It was a little dirty and so I vacuumed it out and my mpg went up. By no means was it clogged. I agree that its not as important as in the past but there is mpg and power gains to be had by a better clean filter.

 

The web page you linked happens to have a link to the Oak Ridge study supporting the claim that dirty filters do not cause a loss of MPG. The degree of dirt was simulated to the extent that the filters distorted and pulled away from the frames. Even at this degree of "dirt" MPG did not suffer.

The only thing that improved by vacuuming out your filter was in your imagination.

You know fully well that fuel trims are constantly adjusted according to the O2 sensor for the correct ratio.

 

Fuel trims do adjust. I dont believe their study. They are basically saying to put a rag over the air filter and you will get better mpg. If the frame was distorted then it got the unfiltered air the engine needed. In real life it dont work that way. A rag is not dirt either. Would you use a rag to get better mpg? I dont think so.