Why is it that some cars with less mpg than mine (53.7) have hypermiler stars and mine doesn't? I already have over 12k miles, so I easily meet the 3k requirement. I feel like a disgruntled kindergarten kid, but by golly, I want my star!

 

You are "Lola"? I notice you have your "City/Highway" set to 50/50%, the vehicle default. This means you need to exceed:

26 = 50% * 52 MPG
30 = 50% * 60 MPG
---
56 MPG vs. 53.7 MPG

Now if your ratio of City/Highway should change, which is something you set in your vehicle profile, say 80/20 percent, you might instantly get your star.

53.7 = (n)*52 + (1-n)*60
53.7 = 52n + 60 - 60n
-6.3 = 52n - 60n
-6.3 = -8n
.7875 = n

79% = highway, 52 MPG
21% = city, 60 MPG

Rounding to make the math easy:

80%*52 + 20%*60 =
41.6 + 12.0 =
53.6 MPG < 53.7 MPG (your number)

I suspect you took the default, 50/50%, instead of something reflective of your actual City mileage / 12k miles verus Highway mileage / 12k miles. The reason I know this is I was on the way to getting my 'star' at 3,000 miles when I realized that my first tank, 290 miles @39 MPG, was all that kept me from getting it.

When I asked if my first tank could be excused, the answer was "Oh NOOOOO! Every tank is important and must be recorded." And then I realized that something else what going on . . .

I do endorse and recommend that you correct your actual highway miles versus city miles since with 12k miles, you finally have a better feel for how it breaks down. As for getting your star, IMHO, the people who deserve a star are those who continue to enter their tanks. The people who deserve a dark entry, not the gray, are those who do more than six tanks and have made an entry in the past six months. Everyone else, at most, can have a gray entry and if less than six tanks, a very light gray entry. The reason is, we should reward those who support Greenhybrid.com and the maintenance of our database.

Let others go for ego tripping numbers but we all know it is the 'luck of the draw.' Some folks just live in hybrid hostile areas yet in spite of their low mileage, they continue to track their efforts. The selfless commitment of these people who have no chance of a mileage based "star" are making a real contribution to our knowledge and understanding. They deserve recognition for their loyalty, persistence and honesty!

Had I lived less than three miles from work, there is no way I could have ever achieved my 'star.' Yet it didn't take long to realize that mileage tagged 'star' is the wrong goal.

If it were my choice, this web site would recognize:

• star + bold - any entry in the last month after the 6th tank
• bold - any entry in the last month
• dark gray - any entry after 6th tank
• light gray - any entry over 6 months old less than 6 tanks

Bob Wilson

ps. You still have a "STAR" in my eyes!

 

Right on Bob! ... and while we are at it, can we have a ratio adjustment for cold climates vs. the SoCal and Florida guys that get summer like driving conditions all year round. My FE does a dump in mid-October, and I know I am not gonna get it back until at least April sometime. A simple adjustment for Latitude would do wonders (although it would not compensate the Denver guys for altitude).

The thing is, you are really competing only against your own record. The real purpose of the database is to give newcomers to hybrids an idea what to expect. The range is a good thing because most people have some idea of how efficiently they drive.

 

While on the subject of the database I thought that I'd just add a couple of comments
The No 1 rated vehicle is ( ahem ) subject to a little scrutiny perhaps.
Farther down the list is a 2nd vehicle, from the same owner, with a more realistic rating but listing 2 tanks in 20,000 miles ( ? ).

A friend who has posted here in the past, Carbot, is in the process of entering his tank-by-tank results on his 04 Prius which he has kept by hand for business reasons. He will go from off the list to No 1 in total miles in one 'swell foop' . 166,000 miles in 45 months.

 

I'm sorry guys, but this silly database insists I use a ONE COUNTRY unit, US gallons. I'm not interested in converting from metric to this every time I try to enter data into the database. My personal info specifies metric units, why can't this be used in the database? Or am I missing something - I spent quite a while trying to figure out how to get the system to accept metric units (litres and kilometers).

So for now, Pearl is deleted from the database.

 

Thanks for all the info. The trouble I have with my commute is that it is not highway driving, nor is it city. I go through 9 traffic lights in a 14 mile commute during which my top speed using the accelerator is 47 mph. I only exceed that when going downhill. The speed limit ranges between 35 and 45 mph. Four of those traffic lights occur within about 1/3 mile of each other. The others occur between a mile and 8 miles apart. The trouble is that my morning commute has 1100 feet of total vertical gain, which kills my mileage. I somewhat make up for it on the afternoon trip home because it becomes mostly downhill.
My question stemming from all that info, is this; what exactly is the definition of highway driving? Is it interstate speeds of 55+ mph, or would 8 miles on a rural 45mph route qualify? Does 4 miles of 35 mph with no lights qualify as city or highway.
I p&g at every opportunity I can. I largely have my commute down to a science, but those stinking hills kill me.
I have become such a hyper mile geek that I relished a mild traffic jam on 128 outside Boston on my way to NH because I ultimately got almost 58 mpg on a tank when my last similar tank was barely 50 with a trip to NH.
As much as i want that kindergarten star, I want it legit, without fudging my city/highway ratio, but I have no clue as to how my daily commute on said route qualifies. Anyone familiar with 102 in North Kingstown and Exeter, RI?

 

The average highway speed in the old EPA profile was 48 mph. The city average speed was 28 mph. Calculate your block time and then figure out the actual ratio of old highway to city speed and have a happy.

Bob Wilson

 

I see this a lot, but 50% driving at 52 mpg and 50% driving at 60 mpg does not give an average fuel economy of 56 mpg.

If you drive 50 miles at 52 mpg, you consume 0.9615 gallons (50/52). If you then drive 50 miles at 60 mpg, you consume 0.8333 gallons (50/60). Combined, you have driven 100 miles and consumed 1.7949 gallons (50/52 + 50/60). This gives a combined fuel economy of 55.7 mpg.

This doesn't always make a big difference, but it can if there is a big spread between the two different fuel economies.

 

Regarding the city/highway percentage specification, yes please do set this to something other than the default! This will give our members the most accurate representation of your driving habits.

Concerning the units, unfortunately we haven't completed the conversions in the code, but you're more than welcome to contact our staff via the Forum Leaders link on the main forum page.

 

I put together a quick spreadsheet to see what how much error occurs with various City/Highway MPG numbers. It turns out 50/50 always has the greatest error:

error - City/Highway model
0.60% - 18/21 GMC Sierra
0.51% - 52/60 Prius NHW20
0.49% - 45/52 Prius NHW11
0.32% - 25/28 Lexus 450h
0.04% - 49/51 Civic II

It has been awhile but I suspect we can combine the two formulas and take the derivative to verify 50/50 is always the maximum error. We can then use it to calculate the worst case error for any pair of City/Highway numbers.

Just using the spreadsheet, the trend is the larger the difference between the City/Highway and the lower the two values, the greater the error.

A simpler answer for the original poster would be to set the default value to the lower of the City/Highway. Or better still, update all of the vehicle mileage numbers with the 2008 EPA numbers. This would essential 'move the goal posts' and make almost everyone a 'hypermiler.'

But I go back to my thinking that mileage numbers are less important than data entry. I would rather see recognition of those who keep their mileage current first with a minimum of say 5-10 tanks and entries within 90 days. Older than 90 days, begins to fade and fewer than 5-10 tanks, even fainter (possibly being dropped from the vehicle averages.)

I'll defer to Kite to post the recommended change. It certainly has merit.

Bob Wilson