Fuel Economy Survey

["Powell, David" <David_Powell@CBSI.com>]

I have a Palm Pilot with software to track mileage data.  I've been through
about 88 tanks of gas.  I dumped the data into a spreadsheet and here's what
I found.
Would anyone care to comment on these numbers?
Some of you must be tracking averages.  How do I compare?

1989 Audi 100 with about 188,500 miles on it.

Overall numbers.  L and M and H
Sample Size = 83 fill-ups
Mean (Average) MPG = 21.99024    <===Typically tracked number.
Median                      = 22.12
Standard Deviation    =  1.9744
Best MPG                  = 25.58
Worst MPG                  = 14.1

Mileage was better with better fuel.
Mean MPG Low octane = 20.73
Mean MPG Medium octane = 21.34
Mean MPG High octane   = 21.89

Fuel was less expensive per gallon with better fuel.
Mean cost per gallon with Low octane       = $0.048539 
Mean cost per gallon with Medium octane = $0.047886  
Mean cost per gallon with High octane      = $0.046047 

FYI
- The software is Kar Kar 2.01
- It tracks mileage, gallons, price, and general octane rating (L)ow
(M)edium (H)igh
- I don't have a brand preference so this fuel is from everywhere.
- I'm in the US so we're talking US Gallons and US Dollars.
- AmsOil oil and filter changed every 10K.