1 Liter Performance How to guide (1 L/100 km = 235 mpg US)

[GreenHornet]

If a person wanted to try and achieve 1L fuel economy (282 mpg Imperial) how would they do it?

That is what this thread is going to attempt to answer

[tjts1]

walk

[GreenHornet]

love the support tjts1 but that is to be expected I suppose.

I mean 1 liter performance is well quite honestly a very big number in the fuel economy world. Most people think 100mpg is a big number out of reach and here I am talking about 282 mpg. Whether you believe it or not this figure has been achieved and documented more times than I can count well maybe not quite that much LOL, but it has been done enough to know it is very real and possible. The problem is how its been achieved has not been detailed in depth and that is something I would like to do with this thread. In doing so my hope is to come up with a road map for anyone who would like to try and achieve 1 Liter fuel economy in the real world driving environment.

A valid argument many people have with vehicles that have achieved 1 Liter level of performance is that they are tested in controlled environments under very specific conditions that would not be realistic in the real world. This argument is well taken and received I mean who would want or be able to drive around at 15mph on average!

Although much can be learned from the eco marathon cars such as the ones that compete in the Shell races. This thread is more geared for real world solutions for real world cars at real world speeds.

So is 1 liter performance possible with real world cars at real world speeds?

The answer is yes and I will prove it here in this thread

GH

[GreenHornet]

So where the heck does a person start? With such a monumental task of 1 liter fuel economy I think its only fitting to look at cars that have achieved it and how they achieved it. I am not going to discuss theoretical cars only cars that have been verified and recorded as having obtained 1 Liter or a minimum of 282mpg fuel economy.

I think its vital first to Determine what the car specifications were as well as figuring out any special engine modifications, advanced driving techniques that would still be quite suitable for current real world driving conditions, and under what conditions they achieved the 1 liter level of performance.

Examples: What car-with what aero mods-with what engine-with what engine mods-at what speeds and-with what advanced driving techniques employed.

This will give us a baseline to work from and determine suitable possibilities with current options we have at our disposal today.

GH

[GreenHornet]

The first car I would like to analyze and discuss is the 1959 Fiat 600 that competed in the Shell Eco Marathons and achieved verified fuel economies of 173 mpg in 1967, 244 in 1968 and 304 in 1973.

This car may or may not have been previously covered in this forum if not I would like to perform an in depth analysis of the car and just how it achieved its 304mpg back in 1973.

First lets look into the 1959 model year Fiat 600 car specs.

Basic Specs:

Sources

#1. Fiat 600 - Wikipedia, the free encyclopedia
#2. 1957 Fiat 600 2a serie detailed specs and performance

Class = City car
Body style = 2-door sedan
Layout = RR layout
Engine = 633 cc OHV I4
767 cc OHV I4
843 cc 100 R7.038 OHV I4 (600S)
Length = 3,215 mm (126.6 in)
Width = 1,380 mm (54 in)
Height = 1,405 mm (55.3 in)
Curb weight = 585 kg (1,290 lb)
CD = 0.5
Top Speed = 61mph
MPG = 41.2

Now we know the basic specs of the Fiat 600 next we need to determine what engine was used in the Shell Eco Marathon version as well as any modifications that were done to enhance the baseline 41.2 mpg of the original.

[MetroMPG]

As well as the average speed(s) of the competition result. That's the key. I suspect most people will find their "real world" speeds don't come very close to that figure.

But it'll be interesting to see those figures if they're available for these "1L" cars.

(PS: I fleshed out the thread title a bit and added US vs Imperial MPG)

I'm enjoying your research. Carry on!

[GreenHornet]

After performing a quick internet search I located the current owner of this vehicle and his detailed website about the car and its history. Inside the website you will find information about the car in addition to others that were built and raced in the Shell Eco marathon races. I found the site to be extremely informative and will pull data from it to discuss the vehicle as I move along.

Owner = Ken Smith
Website = Home - Shell Fiat
Article Link with great pics = http://green.autoblog.com/2013/04/08...iling-history/

I would like to thank Mr. Smith for deciding to share his car with all of us through his website as well as all the information he has collected on the car through researching and talking with the original designers themselves. I hope to contact Mr. Smith at some point to discuss the car further as well as the conditions that were present when the car broke the 1 Liter fuel economy mark.

GH

[GreenHornet]

Originally Posted by MetroMPG

As well as the average speed(s) of the competition result. That's the key. I suspect most people will find their "real world" speeds don't come very close to that figure.

But it'll be interesting to see those figures if they're available for these "1L" cars.

(PS: I fleshed out the thread title a bit and added US vs Imperial MPG)

Hi MetroMPG,

No worries please make changes as you see fit. I make mistakes all the time in my typing and interpretations so I welcome you and anyone else to not hesitate if corrections need to be made here in this thread.

I agree that speed is a very big piece of the puzzle and one we need to analyze in depth for the cars that have thus far achieved 1L performance. I think we also need to determine what is real world speed. I suspect if you ask 100 different people you will get 50 different answers or more depending on region and accepted notions.

My idea of real world speed is between 40-60mph. This covers urban surface street driving as well as highway speed. Obviously you can go much faster on the freeways in some areas but in my state 55mph to 65mph is standard. The majority of in town speed is 45mph or under so I feel as though 40-60mph in my area is a good speed range for real world testing and interpretation.

US speed Limits = http://en.wikipedia.org/wiki/Speed_l..._United_States

I agree that it will be interesting to see just how fast cars such as the Fiat 600 went in order to achieve there 1 liter fuel consumptions. From quick reading I found in several articles that initially the Shell Eco Marathon used a minimum of 30mph baseline speed and then reduced this to 10mph. So I would like to figure out if possible at what speed the Fiat was tested at during its 1973 304mpg run. Hopefully Mr. Smith will have some kind of data on this to share.

GH

[Jyden]

Well - low weight (585 kg) is one reason for good FE. An other is a small frontal arear.
Cars that small today weigh a lot more.

[GreenHornet]

Good Points Jyden and yes you are very correct. Cars today are heavier on average with similar foot prints. However I believe they over come some of the weight penalty with better aerodynamics. Speed and aerodynamics definitely go hand in hand when trying to achieve superior fuel economy.

The Fiat 600 with its estimated .5 coefficient of drag is double what our first gen insight was at .25. This point I find interesting in trying to understand the Shells Eco marathon designers thoughts. Maybe they did not place a big importance on this piece of the fuel economy puzzle. As we know at low speeds aerodynamics and coefficient of drag is not as critical. My question is though how much of a difference could say the Honda Insight aerodynamics at a CD of .25 made on the little Fiat's 304mpg?

I would be curious to find out what the Fiat 600 frontal area is. Anybody out there know this figure by chance?

GH