(This isn't on a Civic, but on my Turbo Maserati) I just recently got back from Grand Junction Colorado and got 31.6 MPG the while going 59 MPH the entire way. I just did a number of improvements to the car (K & N, new oil, and had the car tuned up). I normally average 16.5 MPG with this 240 horsepower beast, but 24 is about average now. Also, those stupid Tornado thingies work pretty well too. That's how GMC makes a 5.7 Liter Yukon get 20 MPG, hence the name Vortec.

So, I'd try
K & N
Synthetic oil (Don't switch back to regular oil if you go with Syn.)
Tune up
and a Tornado
with some Premium gas (91) if you want to.

That should jump your mileage up 4-5 MPG for relatively cheap. Then try I/H/E if you want.

 

does gmc have that tornado thing on a yukon ?

 

dude just get a turbo. I've been granny shifting with mine and I'm seeing the most amazing mpg numbers I've ever seen

 

Ah. the turbo - yes, i understand. but when he said this:

that is what threw me off.

 

GMC uses a swirling vortex intake, which acts like the Tornado (Non moving fan shaped apparatus). That causes the the vortex inside the combustion chamber and creates a more efficient mix of fuel and air. They do not have a Tornado or Turbo in them (unless it's the 6.6 Duramax Diesel which has a turbo.) but they do implement the vortex intake on most of their engines. Compare a Yukon to an Expedition. The GM will do 16-21 MPG and the Expedition will do 13-17.

Since most cars do not use the "Vortec" style of intake, the tornado usually works pretty well. My buddy's Protege 5 gets 42 MPG on an Automatic.

 

Tornado is some kind of fan appartus, correct ??

https://www.hondacivicforum.com/m_97836/tm.htm

 

What happens to the swiriling air when it hits the dead flat butterfly valve in the throttle body? Surely the intake manifold is rifled to provide that swirliness...

BTW, 43.5 MPG in stock engine and loaded down with hurricane evacuation stuff! PWN!

 

I want to comment about the Tornado "Gas Saver," as it did not work for me. I purchased it and tried it on a well-maintained '93 Acura Legend I had and got a reduction rather than improvement in gas mileage. Also, the product actually cut back my acceleration and top speed as it restricted the intake air rather than allowing more air to go into the intake manifold. I had problems accelerating over 80 mph with the car, due to this product. I thought I installed it incorrectly, so I took it out and reinstalled it after rereading the instructions carefully and got the same results.

Officially, I believe that it actually doesn't work for any vehicle and I'd like someone to show me any scientific evidence that it worked for them. The Federal Trade Commission has tested many gas savers and most don't do what is claimed. I think that mileage improvements are actually users being more careful of their driving due to the gas saver and actually trying to get better mileage. I haven't actually seen an independent testing lab study showing the actual improvements these devices claim. The FTC website is http://www.epa.gov/otaq/consumer/reports.htm and it shows some of the supposed gas saving devices tested and the results. They've also tested lubricants like Slick 50, so do a search for those types of tests also. Lawsuits are pending about the false advertising claims of these devices.

Buyer beware!!!

 

A turbo ups your MPG? By how much if you granny drive?

 

Out of all mods discussed here, only turbo works for real to improve MPG. This is because it actually uses some exhaust energy thrown away otherwise. All the rest just increases airflow through the engine, which has nothing to do with engine efficiency[8D]