Modding for Fuel Economy

i’ve wanted to do the exact same things that you are doing to my beater DA, but i always feel like spending the money that some of these mods cost is worse then getting 28mpg vs 33mpg.

just the other day I was sitting outside looking at my car and contemplating putting moon disk wheel covers on it…sounds so tempting to do…hmmmm

The basic things that I’ll be doing next are things that need to be done anyway.

Also, my stock suspension is shot, it’s bad. So lowering the car is fixes a current problem and aids in aerodynamics.

Blocking the lower grill and other minor aero mods, cheap to do and easy to do with a clean fit and finish.

The pricey mods are things like new wheels and other ways to reduce weight and increase aerodynamics (like lips and side skirts). Those are “iffy” to me. However, steelies with disc caps are relatively cheap and I sell my stockers with tires to cover them and then some.


How about just removing unnecessary rotating mass? Most of the things you listed are pretty basic maintenance, but there is a lot you can do for cheap if you are resourceful. Once I get to run a full tank through my car now I can see how much of a difference my work made, but I was getting as much as 32mpg with the automatic gs four door. I should be able to get 36 with ease now.

And as far as aerodynamics play, why don’t you make yourself an undertray?

Belly pan is on my list, but it’s only beneficial when it covers most of the undercarriage. Still doing some research on that.


Well with my 5 spd I’ve changed my habits since about Nov when I got a new clutch and the car started popping out of 4th and sometimes 2nd. I now keep my rpms pretty low, around 2k, but NEVER below 1500 (no lugging!). Like I’ll be shifting to 5th at 40 mph. I started to do it because of the popping out but found I like it anyway as it keeps the RPMs down. I get about 28 on a good day, damn you. And I have a 93 RS… :frowning: (no p/s or a/c, 16s with 40 series)

i wish i could get above 25mpg!!

Lighter flywheel, axles, and wheels can make a big difference. Also you have all of your accessories. So far I have eliminated the power steering and abs (electric, but heavy anyways). Next I am going to installed a solid state a/c system and eliminate the entire stock system. (less rotating mass, less drag, and less moving parts). Along with that I am getting an electronic water pump (more efficient, more reliable, less drag and rotating mass). Eventually I may look into an electronic dry sump, but that is more down the road. Plus with the p/s and a/c removed you can get yourself a lighter ctr crank pulley.

Another thing that I am working on is a hydrogen injection system. It basically runs a multi-celled fuel cell off of the alternator, and then injects 2h2 and o2 into the intake manifold. This refines combustion and with a wide band allows me to run in lean burn during closed loop operation.

I’ve also thought about controlling the airflow under the teg, but I was worried about heat transfer. I heard that not allowing the air to excape before the rear wheels really helps – hence the rear wheel covers in cars like the Insight.

Correct. Wheel skirts are a possibility, but they would need to be painted along with the car to pass for something that possibly belongs there compared to badly designed parts I’ve seen.


Functional diffuser? :hmm:

Diffusers aren’t that great of a mod for cars that aren’t doing 150mph. Vortex generators would be better on the top side along with a full length belly pan and a drop.


man wtf i get 280 miles per tank.

And i mostly baby it for fuel mileage. Spark plugs are two years old, idk how many miles… car has 226,000+ miles, ram air intake, and thats it.

[QUOTE=blizzardrunner;1874118]man wtf i get 280 miles per tank.

And i mostly baby it for fuel mileage. Spark plugs are two years old, idk how many miles… car has 226,000+ miles, ram air intake, and thats it.[/QUOTE]

My car has 168k on it. I’d say replace those plugs soon and might as well do the wires as too. I have a CAI that I want to replace with a modified OEM air box.

I’m adding rebuilding the ICAV to my list because my idle is crazy and that is killing my mpg when I’m in lines and at lights.


I think California gas is killing my mileage too, because i can’t get my car above 25mpg!! even with highway mileage, city is like 21-22mpg, highway is 25mpg. I just did major service too.

Timing Belt, Water Pump, Spark Plugs, Spark Plug wires (NGK), oem fuel filter, brand new aem dry filter intake system, Gaskets on everything possible. Only things i haven’t done are Valve adjustment and changing my pcv valve which im scared to touch because of it breaking off in the intake manifold, which I’m doing asap.

I was getting 23-24 when I first got the db1. The last tank I ran before pulling the automatic gave me 370 miles. It ended up being 29.5mpg, but that was with me playing on some curvy country roads for most of the tank. As soon get a chance to run a full tank through it I will share the new results.

i love the east coast.:slight_smile:

highest mileage was 342miles on shell gas… miami (dadeland) to tampa back down to sarasota… then fill up again…

Well, I love my G2…but I hate the gas gauge…

Not sure how I can from half a tank to almost empty in 50 miles… What’s worse is that at the half tank mark, I was up a good 60 miles over my last fill up. So lame.

So it appears that at best I’ll see 335miles this tank which will be an improvement to 30.5mpg or 1.5mpg better than my average.

After I fill up today, I’ll be changing my plugs, checking my tires and taking measurements for my grill blockers for phase 3. I’ll do my oil change this upcoming weekend, so it’ll be a few days late for the testing but should be in there early enough to contribute to the results.


damn i wish i got that kind of mpg too. if and when u sell the intake let me know, ill buy it from u. beautiful car by the way, i have once just like it except its a gs. and a suggestion is that turbonator thing. im not sure if it really works but they say it gets u more power and better fuel economy.