Chopper - review my thread, it has been updated.
Okay Coastie, thanks for the full-disclosure update! You are certainly calculating your mileage correctly. But your extrapolation of how many more miles you could have run if you ran to empty that gets you over the 400 mark is what was so unbelievable to us. I don't think it's legit to thrown that in, because the 22.5 gallon tank rating does not translate into 22.5 gal of usable fuel... I can put in 21 gallons if I am sputtering and stalling pulling up to the pump. I am pretty sure any of us will run out of gas before we can burn 22.5 gallons.
Here is a tire-size-discrepancy calculator. If you calculate the difference in circumference on your bigger tires and multiply your odo's mileage reading by that ratio, you should end up with a more accurate mileage calculation.
I think there is a little more math to it than that.....
Edit: I would use...http://www.rims-n-tires.com/rt_specs.jsp take the % figure and times it by your miles. The % is found in the speedometer box after the inputs are selected. If this holds true I just banked 18.138 mpg.
Re-edit: Or here http://www.miata.net/garage/tirecalcold.html.....I got 10.7% on the first site and 18.9% difference on the second site due to my larger tires. Which new quote equals 19.52mpg.
But remember I am in the middle of the acetone trials. I just filled up today with 4oz of the juice.
I averaged 17.4 MPG on my way home from Colorado.
I must be doing pretty good... That drive is far from flat... far from it... plus it's windy in all directions, sometimes it's a head wind sometimes it's a cross wind... etc.
I'm still running on the same tank from Rawlins To Ogden (that's 283 miles) And I think my trip o meter is at ~300 (at the dealer or I'd check exact) And I had a quarter tank (on the indicator) left.
We'll see where I end up...
I once drove to payson, az from phoenix.. most of the time I was doing over 80mph.. the fuel mileage was under 14..but I got there alot quicker.. LOL..![]()