Fuel Efficiency and the Yaris

[Yaris Newbie]

So, here's a question from another post that got some response there but might be more suitable here. I was referred here anyway.

Regarding Driving under load.
In rolling hills, where coasting downhill is possible, but it is obvious that I will need to climb the next hill with at least some pressure on the accelerator... should I just forgo coasting down the hill and maintain constant pressure on the gas pedal the entire time (down and up the hill)?

Given these points already made:
Driving slower (to a point) increases gas mileage.
Moderate drafting (please no safety debate) increases gas mileage.

Would it be better to go 50-60 alone or to increase speed to 70 or slightly more to gain a draft off of a transfer truck (18 wheeler)?

At what speed should (the rare times I use AC) I roll up the windows and turn on the AC?

Will a cold air intake improve MPG?

Is there a difference in running the AC at a lower fan speed compared to higher temperature (more red on the circular dial) compared to turning the AC on for a while then off for a while? Or is the compressor doing the same amount of work in all three situations?

[BailOut]

Originally Posted by Yaris Newbie

should I just forgo coasting down the hill and maintain constant pressure on the gas pedal the entire time (down and up the hill)?

On smaller hills, yes. On larger hills, no.

Originally Posted by Yaris Newbie

Would it be better to go 50-60 alone or to increase speed to 70 or slightly more to gain a draft off of a transfer truck (18 wheeler)?

While drafting does indeed offer decreased air resistance, it does nothing for rolling resistance. Going 50-60 alone is much better than drafting at 70. I only draft when I can find a proper vehicle going between 45 and 60 MPH.

Originally Posted by Yaris Newbie

At what speed should (the rare times I use AC) I roll up the windows and turn on the AC?

None. Windows down is always much more efficient than using the a/c. Mythbusters proved as much as well.

Originally Posted by Yaris Newbie

Will a cold air intake improve MPG?

Only if you drive like a testosterone-infested aggressive punk.

Originally Posted by Yaris Newbie

Is there a difference in running the AC at a lower fan speed compared to higher temperature (more red on the circular dial) compared to turning the AC on for a while then off for a while? Or is the compressor doing the same amount of work in all three situations?

The compressor is basically a binary unit, being either on or off. As such it doesn't matter what the fan is set on. If the a/c is on the compressor is clutched 100%.

[petesimac]

Bailout, I heard recently by the so-called experts, that one should roll their windows up when the speed of the car reaches 30 mph, as the drag reduces fuel efficiency -- have you heard this as well?

[Smokey159]

Quote:
Originally Posted by Yaris Newbie
Will a cold air intake improve MPG?

Only if you drive like a testosterone-infested aggressive punk.

LOL, horrible answer.

Before the hack, I did an extensive report on Simota's Carbon Charger... should've saved it.

But anyways, I got an increase in MPG of 1.5MPG. After doing the math, at $3 a gallon, it would take around a year and a half to pay off the investment of the intake. (this number obviously depends on how much you drive per year and the actual price of gas).

Only the "testosterone-infested aggressive punks" LOSE mileage because they want to hear the new sound the intake makes since you can only hear it when you apply more throttle.

Before someone tries to tell me I'm wrong, let me explain. Also keep in mind that I have been an engine builder for almost ten years and I am Dynojet certified to operate their Dynomometers and administer their Power Commander engine management systems.

OK, simply put, if you make an engine more efficient, you save gas. I'll preface this by saying YOU CANNOT CHANGE YOUR DRIVING TECHNIQUES and keep this statement true at the same time.

When you hear people say: "If you introduce more air to an engine, the ECU adds more fuel, making it less fuel efficient" you may tell them that they are HALF right. The fuel mapping DOES introduce more fuel, however this is to keep the air/fuel ratio correct (usually aroun 14:1). Now here is where they are wrong, if you introduce MORE air and MORE fuel to a motor, you make it more powerful, AND more efficient.

If a motor has more power, you don't have to press on the pedal as hard. Opening the throttle less will ALWAYS use less gas then the ECU has added to balance the ratio. As a result, you get better fuel mileage. Think about it this way, with the same amount of pedal, you go further.

Done deal, stop arguing about it. Buy an inexpensive intake and follow the following rules:

1) Reset the ECU after the install by disconnecting the battery for a few minutes, then reconnect it and start the motor. DO NOT REV THE ENGINE, just let it idle for about 5 minutes and then shut it off.

2)Don't buy a high priced intake, this will only make it harder to pay off. CAI are usually higher priced than SRI, but they offer little more in terms of engine efficiency in the real world.

3)Make sure that the design of the intake does not place the Air Intake Sensor too close to the throttle body, this will actually make the engine run rich. for example: Simota's carbon charger is as close as you want to get.

4) Do not change your driving habits, you will see a reduction in fuel economy if you want to hear it. This is harder than you think, it does sound cool.

This is not a smack down post, I just want to clear this up because many people don't truly understand some of the concepts.