Watched an episode on the Speed Channel and it discussed how to get better gas mileage out of your vehicle. A strong recommendation was made for the following items. However, when I read forum posts, these same items are identified as "go fast" items and fuel mileage never comes up.

Your thoughts.

. An after-market air filter system that is non-restrictive
. Good spark plugs
. Synthetic oil and other synthetic products
. Computer Tune
. Catback exhaust system
. Long Tube Headers

 

All of those mods increase the efficiency at which fuel is burned. The more efficient that the fuel burning process is, the more fuel that can be used by the engine. This results in higher engine performance and higher fuel efficiency. Problem is if you increase the performance, you also increase the rate at which you burn the fuel. Get it??

 

The items you list generally will not decrease your fuel mileage, unless you just can't keep your foot out of the gas pedal. Like mentioned above, better breathing and exhaust flow should help you out.

 

A simple demonstration of how this works is with your mouth:

Open your lips as if your were going to say "oh". (Small opening)
Then take 3 big breaths as fast as you can without opening your mouth anymore.
Notice how much energy it takes.

Now open you mouth as wide as possible and take 3 more big deep breaths.
Notice how much easier (less energy) it is.

Now if you were to keep trying to breath hard with your mouth wide open, you'd hyperventilate AND tire yourself out very quickly.

And there you have it. Letting the engine breath easier doesn't mean that you have to push it harder.

 

Above is the weirdest analogy I have ever read.......

 

Must be why I woke up on the floor next to my computer about 2 minutes after trying it.

 

 

LOL! Hey, I try!

 

Like others have mentioned, the mods you listed help the car to combust air and fuel better. This means that if you apply the same conditions as before the mods were added then the engine would require less effort to meet the same performance... you have made the engine more EFFICIENT. There are less mechanical losses in the propulsion process after the mods.

However, let's say you run your car at 5000rpm for one minute while it is stock and it uses up 0.X gallons of gas. Now you add new plugs and wires, fresh oil, a less restrictive air filter, headers and a catback and you run the engine at 5000rpm for a minute again. The engine is now able to take in more air than it did in the original one minute interval and adjusts by adding more fuel than before which will give you more horsepower at this rpm but will consume more fuel than it did stock.

So depending on how you drive the car will depend on whether your mileage gets better or worse. Most likely, you will push the car a little harder after the mods and therefore use more fuel.

The bottom line is, please don't spend a few thousand dollars on those mods if the only thing you want is better gas mileage.

One more thing, a tune for better performance is not the same as a tune for better gas mileage. For the C5 I believe they come from the factory pretty rich to be on the safe side, so tuners will usually lean out some of the rpm band to improve both performance and fuel economy. However, you can get tunes to get even better fuel economy that will hinder your performance from stock.

 

It's funny cause i tried it

 

Anything that reduces the restriction of air getting into or out of the engine will help increase the fuel mileage as the engine can use that power to move the car forward instead of getting the air in and out. The synthetic oils reduce the fiction and associated losses where used compared to normal oil. The spark plugs help the combustion process to get a more complete burn, if the old ones are worn. The computer can be tuned for better fuel economy as stated previously. Other things you can do is get a lighter flywheel, lighter wheels, Lighter drive shaft, basically, lighten the car and eat a salad a few times a week because that car has to push you around too. This will all increase the cars performance and increase the fuel economy.

 

I have headers cold air intake hurst shiffter.And I can get 32mpg.Also Magna Flow exhaust.On reg gas. Go figure.

 

I get 10-12 MPG in the city BUT I get 27-31 in the highway. Got to love big cams

 

I've seen pornos that started like this.

• 3" wood block under gas pedal.

 

You've probably seen me then.

 

All these things are good for better milage. But a engine, is basicly a big air pump. The more air/fuel you can get in it, the faster it goes. But to safe gas, you want to eliminate as much friction that the 'Air Pump' has. So less restrictive air flow, super slippery oil at the bearings and. . . Drive like there's an egg between your foot and the gas pedal. That means using less fuel to get the 3000 pounds up to speed, and trying to keep as much forward velocity as possible while on a flat highway. So that means trying to eliminate any stops and rapid starts. That's not really possible in everyday traffic driving, but trying to get up to speed and coasting along on downhills and using as little gas to go up hills will always give you better gas milage, no matter what vehicle. This is why the 55 mph speed limit was designed, or implemented.

Years ago in the sixties, a lot of cars had something called an 'Econometer' which is in reality just a vacume guage in reverse. It had a white needle which sweep across a green and red sweep range. The object was to keep the needle in the green (Or high vacume) range, but if you stepped down hard on the gas pedal, ( Decreasing or low Vacume) the needle went into the red, or bad gas milage range. FWIW

 

Mods listed below in sig and still get 27-28 HWY, BUT 15-16 in the city

 

Any modification that decreases parasitic friction on the engine will increase fuel economy assuming driving style does not change. FI users report increased fuel economy but this is subject to a number of factors.

Crusing speed effeciency is probably the most important part of fuel economy. The question is how hard is your engine working to maintain your speed. For 6 speeds and A4s with the 2.73 gear option, your engine is running slower at cruise, but with less power. These cars will see the most improvement from the modifications you listed since the engine won't need to dump in as much fuel to get the power needed. Cars with aftermarket or performance option gears have plenty of power at cruise but the engine is turning faster and more R's = more burnt gas.

 

Maybe, if you keep your foot out of it, but minimal gains at best.
Will help if yours are worn, but not if they aren't. Minimal difference unless yours are showing obvious signs of problems (DIC codes).
If it's lighter weight, like 0w20, then less drag to pump it. Might sacrifice wear and tear on your internals though.
Depends on who tunes it, but this is probably where most of the gains can be made. Most tuners are looking for more HP though, so might be hard to find a person who can tune for MPG.

Not on the Vette. No HP, no MPG, nothing but ear candy.
If anything this will be the worst thing you can do for your gas mileage. Puts the 02 sensors, that control the fuel mixture, too far down stream to be effective and doing so.

 

Took me 3 minutes to come around!