Ok, this is a serious question, but feel free to tell me I'm dreaming...

Are there any mods that will increase fuel efficiency? I'm driving a stock '04 Sedan with 140k on it. I've only had it a little over a week and averaged about 19 mpg on my first tank, which I understand is pretty normal. I'd like to do better if I can. I'm not racing or cruising, and not really concerned with increasing HP. It's a daily driver, so...

There, I said it. Now let the laughter begin. And, hopefully, a few serious comments too.

 

get a z tube that will help a bit

 

What kind of driving do you do?

 

So far, it's been a mix of city/hwy, to and from work and church. Short trips of about 12 miles one way, with about 5 or 6 of that being on the highway.

 

Seems no one must care about the EPAs fuel economy ratings any longer.

Simply amazing after the $5 per gallon gasoline we saw in the summer of 2008.

Even if you bought a car used - it's on the web at http://www.fueleconomy.gov/

Really fuel economy cannot be a high priority if one is buying a G35 with a or any car with a 3500 cc high compression gas engine as a daily driver.

Consider that 90% of the world's gas powered passenger car production is with engines less than 2000 cc in displacement.

This is the reason a G35 loses 50% of its original purchase price in three years and a Toyota Prius loses maybe 20% of its price in the same period.

An original owner In the city/ suburban driving I do, with 67K miles on the clock I get about the same mileage, with fairly restrained driving. Of course when I bought the car new in 2003 gasoline was retailing at about $2 per gallon.

Just good preventative maintenance will keep fuel economy at its best. Clean air filter/ tire pressure at factory cold specs.

Be glad you don't have an E46 M3. A client has one and he reports not better than 15 mpg in relaxed driving.

 

A z-tube isn't going to increase MPG. Keeping your car well maintained (i.e. using a clean air filter) will help. Your best bet is just to drive conservatively.

I average about 300 miles to the tank. I've been able to squeeze out 400 miles out of a tank, though. The only difference being my driving style. I lost my wallet, so I had no ATM/debit/credit card to buy gas. So I was just REALLY easy on the gas (like 80 year old grandpa status) and never drove over 65mph on the highway.

You may not think you drive "aggressively," and you may not be. But I'm betting that you can still take it easier...unless you already drive like an 80 year old grandpa.

 

Here are a few things you can do off of the top of my head:

1. Use higher octane gas
2. Install K&N air filter
3. Use 0W-XX Mobil 1 fully synthetic oil
4. Use K&N oil filter
5. Look into spark plug upgrades
6. Reduce the weight in your car (obviously)
7. Use cruise control
8. Get your air/ fuel ratio tuned
9. Check tires for abnormal wear and get an alignment if necessary
10. Make sure tires are inflated properly
11. Install an under body cover and diffuser

That's as much as I can think of. Many of the things I have listed aren't proven, but at the same time, they haven't been disproved.

Let us know what you do and post back your results!

 

wheel well covers and disc rims, lol say goodbye to brakes

 

Modifications aren't really going to do much as far as fuel economy goes. If you're car is running a bit rich, it could benefit from leaner tune, but even that doesn't buy too much.

The only way you will really improve on fuel economy is by changing driving style. Keep speed to 60MPH and less when cruising, and drive like a granny at all other times. This could easily get you a 5MPH+ improvement overall.

Remember, air drag is dependent on the SQUARE of the velocity. So as you go faster and faster, drag increases by the square. Its not a linear relationship. So if you can keep your speed down, drag is greatly reduced and fuel economy increases.

And stop the start/stop driving. Gradually accelerate, gradually brake. Remember, that braking is a loss and greatly impacts fuel economy.

It takes a lot a fuel to accelerate your car from 0-60MPH. Every time you brake, you are virtually throwing out the same amount of fuel - all that kinetic energy generated from the fuel is now being throw out as heat. Hence, the reason city MPG is so much less than highway MPG.

 

Possibly Reset your ECU and change your driving habits and allow the ECU to relaearn these new driving habits.

I consistently get at least 360 miles on my G between each fillup. And everytimg i fill up, I usually still have 2.5 to 3 gals in the tank still.

Also, I used 91 Chevron gas religiously. However, I recently switched to 89 Chevron and my mileage jumped all the way to 430 with 1.5 gals left in the tank. I've been tracking my mileage for the last few weeks and used 91 for a trip to Vegas recently. Used 89 when i got back, and I got better mileage on my normal Oxnard-Fontana turn around trip (220 miles round trip). Still got 2 more fillups i need to do, to verify that this is the trend and not an anomaly.

Also, using ur Cruise control is your best bet. Accelerating and Decelerating with your cruise control works wonders also. You'd be surprised what it will do. But I would definitely use the 89.

 

air pressure in tires and maintain it

not really any mods that will pay off for MPG

example:

a CAI will cost $300+ and might give you 2-5 miles more per tank of gas.

you would have to drive a lot or the price of gas would have to be really high.

Same is true with most mods on any car, they are more cosmetic than performance.

 

1) New OEM or Napa Gold $13 air filter every 15K miles
2) Clean the MAF sensor with electronics cleaner every 15K miles
3) Replace plugs with OEM NGKs every 60K miles
4) Air tires up to 35 psi
5) Have front/rear alignment set to fractionally toe-in (0.04 total toe). At speed the toe will be around 0.
6) Using Tirerack.com, buy OEM size tires that are the narrowest for their size. Your tire size is "215/55R17", but a 215 width across makes varies. One might have a 7" contact patch and another 7.5". You want the narrow one to reduce roll resistance.
7) Use 91+ octane fuel
8) Keep the tank over 1/4 full
9) Remove loose gear from the car, especially the trunk
10) Keep highway speeds at 70mph or below
11) Use cruise when doing extended highway driving

In the winter, you're going to see ~15% lower mpgs due to extended warmups and lower btu winter gas. These cars don't see exceptional city mpgs, but they do pretty good on the highway. I've seen as high as 29mpgs averaging 65mph on a topographically flat 500 miles, but usually I see around 26mpg in 100% highway driving averaging 75mph on rolling terrain.

 

higher octane will not save you money in the long run, as your difference in MPG is less than the price/gal difference.

also, with some drafting, I've gotten my MPG kicked up a few MPG...

j/k... drafting is very dangerous.... and your life is not worth the $42.67 you'll save each year.....

otherwise, everyone is correct regarding tire pressure, driving style (including cruise control and MPH), and car weight

 

lose weight, follow a regular PM program. DaveB covers most things in his post.

 

The driver mod is prob the best thing you can do. Learn to drive like there is an egg between your foot and gas pedal and your fuel economy will go up.

Downside to this is if you do it right, young people behind you will get mad and flip you off as they pass you on the left