Where Did 84 Mpg Come From?

[CheeseheadEarl]

On which setting?

Running electrical accessories (e.g., air conditioner) decreases fuel economy. Operating the air conditioner on "Max" can reduce MPG by roughly 5–25% compared to not using it.

http://www.fueleconomy.gov/feg/factors.shtml

5% is something you ain't gonna see on a 55hp motor. It'll be closer to the top end. AC compressors (depending on sizing) can pull up to 20hp. Obviously a little cab like the Elio won't need one that big, but they do rob power and economy.

 

[Jim H]

5% is something you ain't gonna see on a 55hp motor. It'll be closer to the top end. AC compressors (depending on sizing) can pull up to 20hp. Obviously a little cab like the Elio won't need one that big, but they do rob power and economy.

Welcome to the forum and we appreciate your comments. Most people are very friendly and helpful and the forum has all the latest information. Welcome to the journey

 

[Craig]

Just found this.

The "new" EPA mileage tests are run with the AC on.

 

[goofyone]

Didn't someone post the goal was 84 with AC running, meaning it should be somewhere around 90 MPG?
View attachment 1071

The EPA fuel economy testing on cars since the 2008 model year include testing with the AC running.

http://www.fueleconomy.gov/feg/ratings2008.shtml

http://www.fueleconomy.gov/feg/fe_test_schedules.shtml

Update: Craig you must have beat me by just a few seconds.

 

[olddog1946]

I personally would drive the Elio even if it only got 60 mpg. I liked the styling of the P3, but absolutely love the P4. I saw somewhere that they did get the P3 up to 81 mpg, with the P4 changes the result of not making the 84 goal. My first thought was why the heck are they concerned with the mpg of a motor they are NOT going to put in the rig. Get the motor that it will come with and then worry about the mpg.

 

[GEC]

Are you familiar with the song "Just my Imagination"? BINGO!, that's it!

 

[Joshua Caldwell]

If you meet the goal with the old motor based on aero tweaks, then you should blow by it with the new motor.

 

[olddog1946]

If you meet the goal with the old motor based on aero tweaks, then you should blow by it with the new motor.

I have to say it would not hurt my feelings any if they beat the 84 goal.

 

[MJZ]

I don't know the answer to the OP's question, but if I had to make an educated guess. I would say that since the original engine came from a Geo Metro, and the 1995 Metro 3cyl manual engine got 37 City, 44 Highway, and we've all heard Mr. Elio say (paraphrasing) "...at highway speeds half the power is going to pushing air, Elio is half the width, so twice the MPG" So, using the original engine specs and ignoring power to weight ratios, 1/2 the size of the original car size would give us an estimated 74 city, 88 highway. So it's pretty easy to gauge where the number might have come from. Factor in how much less air the Elio pushes vs the '95 metro, calculate weight differences, and knowing the original engine specs/economy you can extrapolate an estimated MPG range for the prototype.

Again, not 100%, but that's how I would do it during original concept/design and bench-marking.


Some things I noticed while looking at the P4 that could be done to increase MPG. The fenders are fairly blunt, whereas not a wall , they are not as streamlined as they could be. A simple center-line ridge, reducing the head wind facing surface will decrease wind resistance and increase slipperiness. Also, simply reducing the width of the rear tire will reduces ground friction on the drag wheel as well as allow the rear to be further tapered (even if only that the bottom) this will reduce rear turbulence and eddies that cause rear drag as the air leaves the vehicle surface. There has been talk about the grill size being reduced. And I do fully stand by the addition of a small turbo, increasing power to weight increases efficiency. Too much gas is wasted during the "getting up to cruising speed" portion of highway travel. Since turbo's only really add performance under 80-100% throttle, this is perfect for increasing power to get up to speed without struggling and sucking down gas.

Also, to increase city MPG and appeal to a larger market (still don't see this as a city car like the prius) How hard would it be to add one of those "engine off when the car is stopped" options? I haven't researched what goes into those, but I'm pretty sure it's nothing extra other than programming. That would greatly increase the MPG for the city specs AND increase market desirability.

Anyway, just my 200 cents.

 

[Jim H]

I don't know the answer to the OP's question, but if I had to make an educated guess. I would say that since the original engine came from a Geo Metro, and the 1995 Metro 3cyl manual engine got 37 City, 44 Highway, and we've all heard Mr. Elio say (paraphrasing) "...at highway speeds half the power is going to pushing air, Elio is half the width, so twice the MPG" So, using the original engine specs and ignoring power to weight ratios, 1/2 the size of the original car size would give us an estimated 74 city, 88 highway. So it's pretty easy to gauge where the number might have come from. Factor in how much less air the Elio pushes vs the '95 metro, calculate weight differences, and knowing the original engine specs/economy you can extrapolate an estimated MPG range for the prototype.

Again, not 100%, but that's how I would do it during original concept/design and bench-marking.


Some things I noticed while looking at the P4 that could be done to increase MPG. The fenders are fairly blunt, whereas not a wall , they are not as streamlined as they could be. A simple center-line ridge, reducing the head wind facing surface will decrease wind resistance and increase slipperiness. Also, simply reducing the width of the rear tire will reduces ground friction on the drag wheel as well as allow the rear to be further tapered (even if only that the bottom) this will reduce rear turbulence and eddies that cause rear drag as the air leaves the vehicle surface. There has been talk about the grill size being reduced. And I do fully stand by the addition of a small turbo, increasing power to weight increases efficiency. Too much gas is wasted during the "getting up to cruising speed" portion of highway travel. Since turbo's only really add performance under 80-100% throttle, this is perfect for increasing power to get up to speed without struggling and sucking down gas.

Also, to increase city MPG and appeal to a larger market (still don't see this as a city car like the prius) How hard would it be to add one of those "engine off when the car is stopped" options? I haven't researched what goes into those, but I'm pretty sure it's nothing extra other than programming. That would greatly increase the MPG for the city specs AND increase market desirability.

Anyway, just my 200 cents.

Another great comment and the expertise of the forum members is increasing. Not having experience in these matters I find information like this to be fantastic and easy to understand. Thanks, and I look forward to more comments like this.