500 Mile Range and Tank to Empty Test (1 Viewer)

[TeCKis300]

513.9 miles to bone dry empty. With my larger 33” tires, the actual corrected driven range is 544 miles.

To be clear, this range is with a recently installed LRA 12.5 gallon sub-tank. Roughly 70% highway, 30% local mix.

I also did a test as I had an external fuel can with me. I ran my main tank and aux tank dry to engine stall, to test how much actual range there is when the low fuel light comes on – 45 (local) miles.

The theoretical capacity is 24.6 gallons main tank and 12.5 gallons auxillary, for a net capacity of 37.1 gallons. Full up empty, I pumped 35.13 gallons into the vehicle. Calculated MPG for the tank was 15.5 mpg.

 

[Markuson]

Aaaa!!
Let me tweak that fer ya... (was thinking my vision problem suddenly got much worse. )

 

[FinallyGotOne!]

This is great. Let me ask some clarifying questions, please:

1. Do I understand correctly that you measured only a 45 mile range after the low fuel light came on? I believe I've done more than that and still filled up with only 22 gallons or so. I could be wrong, but perhaps you were only getting ~10 mpg in local conditions.
2. Were the winds fairly benign during your test? Any significant head or tailwinds? Elevation? I've found even 5-8 mph winds will significantly effect my mpg.
3. I am very intrigued by the fact that you were only able to put 22.63 gallons into the main tank, assuming you put a true 12.5 gallons in the AUX. Reality is probably less than 12.5, which means you put less than 22 gallons from empty to full in the main.

I think I've put well into the 22's into my tank and that I've run very close to the high 40 miles after the light. Maybe I was way closer to a major fail than I realized!!!!

Regardless, I think you're a "Model Mudder" and I appreciate the data! GOOD STUFF!

(I'm also jealous of that AUX. I want one, but know I will never do it!)

 

[Hoosier Daddy]

If you were getting 15mpg and ran 45 miles after the light came on, that suggests a 3 gallon reserve when the light came on. I thought the conventional wisdom was that the reserve was felt to be 5 gallons, but I'm not sure I've ever seen anyone actually test it like you did. Still, I wonder if there could have been 2 gallons hiding in your tank when you stalled, to account for the 2 gallon difference between your theoretical capacity and what you put in. Do you remember if you were on a hill when you stalled?

 

[Markuson]

I have stuffed just OVER 24.6 gallons in my main twice (before my LRA sub) and confirmed that there is closer to 4-5 gallons in there when the light comes on...at least on my 2008.

Not recommending anyone do this (for several reasons including protecting your pump), but the capacity is definitely in there.

 

[terdrocket]

I have stuffed just OVER 24.6 gallons in my main twice (before my LRA sub) and confirmed that there is closer to 4-5 gallons in there when the light comes on...at least on my 2008.

Not recommending anyone do this (for several reasons including protecting your pump), but the capacity is definitely in there.

This has been my exact experience as well.

 

[Ninja Cruiser100]

Mine as well. I wonder why Mr T felt it was necessary to have such a large reserve?

 

[TeCKis300]

This is great. Let me ask some clarifying questions, please:

1. Do I understand correctly that you measured only a 45 mile range after the low fuel light came on? I believe I've done more than that and still filled up with only 22 gallons or so. I could be wrong, but perhaps you were only getting ~10 mpg in local conditions.
2. Were the winds fairly benign during your test? Any significant head or tailwinds? Elevation? I've found even 5-8 mph winds will significantly effect my mpg.
3. I am very intrigued by the fact that you were only able to put 22.63 gallons into the main tank, assuming you put a true 12.5 gallons in the AUX. Reality is probably less than 12.5, which means you put less than 22 gallons from empty to full in the main.

I think I've put well into the 22's into my tank and that I've run very close to the high 40 miles after the light. Maybe I was way closer to a major fail than I realized!!!!

Regardless, I think you're a "Model Mudder" and I appreciate the data! GOOD STUFF!

(I'm also jealous of that AUX. I want one, but know I will never do it!)

Spot on. That's why I noted (local) miles in the reserve test as I tried to stay near Costco which is my preferred gas station. Especially as we're talking about over $100 fills. Most of the tank was driving from Vegas to LA to San Diego. The latter part was running errands around city streets, including with the reserve test. ~11mpg would be typical for me in this type of driving, so 45 miles represents 4.09 gallons.

With 4.09 gallons reserve:
Best case for a stock vehicle on the highway @18mpg = 72 miles.
Worst case I've had towing/headwind/hill @8mpg = 32 miles.

I log every gas fill in a notebook. Max I've noted on on a few occasions running into the reserve is 22.4-22.6 gallon. I never intentionally overfill, as it only wastes gas, with the added risk of flooding the charcoal canister.

 

[TeCKis300]

If you were getting 15mpg and ran 45 miles after the light came on, that suggests a 3 gallon reserve when the light came on. I thought the conventional wisdom was that the reserve was felt to be 5 gallons, but I'm not sure I've ever seen anyone actually test it like you did. Still, I wonder if there could have been 2 gallons hiding in your tank when you stalled, to account for the 2 gallon difference between your theoretical capacity and what you put in. Do you remember if you were on a hill when you stalled?

To answer your other questions not yet touched on above.

I can't say if the hidden two gallons is in the main or aux. Likely a bit of each with majority in the main?

Most modern naturally aspirated fuel injected cars run 30-45 psi rail pressures. So as soon as the pump draws any air, the fuel pressure collapses and the engine stalls. Since I consciously was looking for the empty, I was watching for sloshing and hills. When it stalled, I was on a local side street, completely flat at 20mph. It stalled without warning and immediately, and I pulled over onto the shoulder (without power steering assist).

 

[RET2]

Very informative, thanks. Good FWIW info

 

[Scylth]

TeC,

Thanks for the good math.

How aggressively were you driving during this test? I typically drive my 200 pretty soft to conserve fuel. I have the 24 gal aux tank, with 33.8” rolling radius tires, so am curious to ratio-up your math to estimate my real range.

 

[TeCKis300]

For this drive, I'd say on average, the tank was driven on the moderate end of the spectrum, averaging ~75mph on the highway. I'm usually on the aggressive side (>80mph) but my wife also drove a chunk nd she's on the conservative end (70-75mph).

We all know local roads is what kills mpg, with stock rated at 13 city / 18 highway. The mix was likely more 80% highway / 20% local. Reserve test was all local.

With my larger 305 width ,33" tires, and overall driving style, I'm typically 1.5-3 mpg less than rated mpg. I track my mileage every tank and the numbers shown in the test are pretty consistent with my historical numbers.

 

[Dan Higgins]

Great info. Thanks. You are far more disciplined and scientific about this than I will ever be. So I appreciate the time and effort (and gas) it took to do this!