What's your fuel economy to weight ratio? - Page 3

95metro · 05-25-2006, 08:59 AM

Quote:

Originally Posted by Compaq888

we should definetly figure out some kind of a formula for weight and mpg. Because some of us don't have 3 cylenders, lightweight car, manual transmission, honda engine, small displacement motor. With the formula with can show who made more progress. Of course the thing under our sigs that showed a % hypermiling was accurate too.

What about a simple point system with a baseline of 50? For every mpg over the EPA average you get an extra point (or lose if under). My Metro would score a 47 right now.

Anyone with a severely modded vehicle should take the average of the EPA averages for every vehicle they've borrowed major parts from (chassis/body, motor, transmission) - they should end up with a very high score then.

This way even an F350 getting higher than the EPA average could beat any other vehicle.

Just a suggestion. I know it's not hard, cool numbers like mpg/pound (wouldn't mpg/tonne produce a more sensible number?), but at least it would keep everyone in the running vehicle type be damned.

Matt Timion · 05-25-2006, 09:31 AM

I like where this idea is going. if we are able to decide on a formula that we all agree on then I can add this to the garage. When you pull up a vehicle you'll see year, make, model, 90-day mpg, curb weight, and this ratio. We can even do a top-ten.

GasSavers_katman · 05-25-2006, 09:33 AM

Not fair! The heavy vehicles are only going to improve a few MPG. Light weight one will show a bigger improvement for the same mods. It needs to be a percentage over or under the EPA.

95metro · 05-25-2006, 09:53 AM

Quote:

Originally Posted by katman

Not fair! The heavy vehicles are only going to improve a few MPG. Light weight one will show a bigger improvement for the same mods. It needs to be a percentage over or under the EPA.

But isn't that the point? A point scale would show just how far you are willing to go to get the mileage OR the maximum that the vehicle can achieve.

Performance is the same way. You can add a lot less to a lighter vehicle to make it rip the hair off of a heavier one.

Any point system will eventually favor the lighter/smaller/modified vehicle simply because the large/heavy/powerful one is already running at a deficit.

zpiloto · 05-25-2006, 09:56 AM

Did we not already have this with the last gas log that showed where you were in relation to EPA values. What wrong with that?

95metro · 05-25-2006, 10:02 AM

Quote:

Originally Posted by zpiloto

Did we not already have this with the last gas log that showed where you were in relation to EPA values. What wrong with that?

Yeah, we did, but everybody seems to asking for a ratings/comparison based on MetroMPG's mpg:weight ratio which won't work since it's only one number in a huge field of numbers. It's like comparing a Vette and a Viper based on HP ratings alone.

I thought a base of 50 puts everyone on level ground and then you just add/subtract from there to see how your vehicle/driving compares. A point system is a great idea I think. I think percentages can be misleading at times since you don't necessarily immediately know what the percentage stands for.

thisisntjared · 05-25-2006, 10:10 AM

i think its important to have both the efficiency-weight product and the over epa percentage. because some cars are a lot easier to squeeze efficiency out of than others. there is no need to replace one with another. also weight is usually a good indicator of how big a vehicle is. you could do frontal area but that really only covers so much and its a more difficult statistic to get your hands on. i am totally unaware of my cars frontal area. but i know its weight.

also i think these formulas should be kept simple. any more an we will have to start taking derivative of the torque curve at the mean rpm and dividing by the blablablabla nobody cares.

2 simple formulas:

efficiency-weight product
= lbs * mpg /1000
this shows a general idea of the overall designed efficiency for the car in its class as compared to others, both the dealers design and your modifications

hypermiler percentage
= 1 - (epa mpg / actual mpg)
this shows a general idea of the improvements youve made over the factory design and average driving style.

also there should be some way of taking two averages. this was my tick with the old gaslog. my ending average mpg was my average since december, back when it was 33-34mpg. the last 10 tanks were over 38mpg and the last 3 over 40mpg. i think the average of the last 5 tanks should be the average that is displayed. that will also cause a much more dynamic top 10

sorry for another novel status post but i dont know how i could condense it. trust me its worth reading

95metro · 05-25-2006, 12:42 PM

Quote:

Originally Posted by thisisntjared

efficiency-weight product
= lbs * mpg /1000
this shows a general idea of the overall designed efficiency for the car in its class as compared to others, both the dealers design and your modifications

But could what does the resulting number mean? I don't understand it at all...