MPG/Range record for me!

I hit an all time high this week for MPG! I had been getting a max of 330ish range for the longest time... ever since I replaced my muffler with an aftermarket "performance" muffler.

I just hit 411 miles on a single tank and filled up 21.3 of 22 gallons!
That's 19.3 MPG!

Noted conditions/changes:

• 91 octane gas
• Unplugged battery to reset computer (following exhaust change)
• Air up tires to 36 psi
• Drive it like a Stick Shift
• Highway primary, city moderate...

The biggest and immediate result was from the resetting of the computer. For those who have aftermarket exhausts and have not reset the computer... DO so! You'll be happy!

WOW, if I saw 19+ and you had a feather, we would both be tickled:p

Nice, much better than I get but I run 33s. I will be doing some highway driving this weekend which I usually dont do in the VX. I will update with my official highway mileage. Its usually hard to figure out because bigger tires throw off the ODO

Quote:

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Originally Posted by VXorado

Nice, much better than I get but I run 33s. I will be doing some highway driving this weekend which I usually dont do in the VX. I will update with my official highway mileage. Its usually hard to figure out because bigger tires throw off the ODO

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My 32" tyres throw the ODO off 6.84%, so your 33's would be off about 10.2%.

Calculate your MPG as per the ODO in the normal manner, then multiply by 1.102.

PK

Hmmmm, I might try this tomorrow. Tell me about resetting the computer. What does that do? Also, how long do you disconnect the battery?
Peace.
Tom

So what aftermarket "performance" muffler did you go with?

To reset the computer just unplug the battery for about 1/2 an hour. Learned this from a different thread on here. Glad I did... immediate difference. The VX RAN differently on the highway. The motor was actually quieter and smoother...

As for the muffler...
After I tried the Flowmaster Super40 and loved the sound but hated the MPG, torque loss, etc... I went with a Cherry Bomb Vortex. This is very similar internally to the Flowmaster, with an added element... glass packed innerds!
Noise level... if the Flowmaster was a 10 at it's loudest, the Vortex is a 7.
Performance/Torque... Stock is a 10, Flowmaster is a 5, and the Vortex is a 9! Barely any loss. (Rephrase... barely any loss now that the computer is reset!)
MPG... Stock I had max range of 370 miles. Flowmaster, around 327. Vortex... 411. BUT, before I did the computer reset, the Vortex had 327ish too... So, it's very possible that the Flowmaster could have been better if I had known about the reset trick back then.

Also note... I'm NOT a Grandpa on the road either...
AND, this is the 3rd week in a row that I've had mileage in the 400 range.

Now... before I get too excited. Could someone tell me the variance to multiply by for 255-55-18 tires?
Being that these are wider than stock and not taller (by much) I don't see the numbers changing too much. Could be wrong...

Thank you!

Might be your overinflation of the tires (OEM recommendation is 29 PSI I think?) more than anything else. If you google "hypermiling" (sp?) you'll see that overinflating the tires is one of the tricks they use to increase mileage pretty dramatically.

Quote:

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Originally Posted by PK

My 32" tyres throw the ODO off 6.84%, so your 33's would be off about 10.2%.

Calculate your MPG as per the ODO in the normal manner, then multiply by 1.102.

PK

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I was planning on using google maps and calculating the mileage by using the known miles from one location to the other... but I think your method is a bit easier. Thanks.

Quote:

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Originally Posted by SilverBullet75

To reset the computer just unplug the battery for about 1/2 an hour. Learned this from a different thread on here. Glad I did... immediate difference. The VX RAN differently on the highway. The motor was actually quieter and smoother...

As for the muffler...
After I tried the Flowmaster Super40 and loved the sound but hated the MPG, torque loss, etc... I went with a Cherry Bomb Vortex. This is very similar internally to the Flowmaster, with an added element... glass packed innerds!
Noise level... if the Flowmaster was a 10 at it's loudest, the Vortex is a 7.
Performance/Torque... Stock is a 10, Flowmaster is a 5, and the Vortex is a 9! Barely any loss. (Rephrase... barely any loss now that the computer is reset!)
MPG... Stock I had max range of 370 miles. Flowmaster, around 327. Vortex... 411. BUT, before I did the computer reset, the Vortex had 327ish too... So, it's very possible that the Flowmaster could have been better if I had known about the reset trick back then.

Also note... I'm NOT a Grandpa on the road either...
AND, this is the 3rd week in a row that I've had mileage in the 400 range.

Now... before I get too excited. Could someone tell me the variance to multiply by for 255-55-18 tires?
Being that these are wider than stock and not taller (by much) I don't see the numbers changing too much. Could be wrong...

Thank you!

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Here's a website I just found that lets you compare tires sizes and the exact difference in ODO readings. Wider shouldn't be a problem but the height will throw the ODO off because one rotation of the stock tire will go a further/shorter distance than a differently sized tire.

http://www.1010tires.com/TireSizeCalculator.asp

Thanks!

So, it looks like my Nitto Terra Grapplers are 1.819% different from stock. I tried doing what you said, multiplying my MPG (19.3) by 1.819, but I don't think I'm doing something right, because I got 35.1067... now what?

Quote:

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Originally Posted by SilverBullet75

Thanks!

So, it looks like my Nitto Terra Grapplers are 1.819% different from stock. I tried doing what you said, multiplying my MPG (19.3) by 1.819, but I don't think I'm doing something right, because I got 35.1067... now what?

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I think you want to multiple by 1.01819... which would be close to 19.65.

Interesting...
In my mind, if the tire is rotating 1.8% faster, and at speedo 60, true speed is 58, wouldn't that mean that the ODO mileage is off by a bit... should be less than 411... which would mean that the MPG should be lower instead of higher. ??

I'm in no way a mathematician... actually, I suck at math. So, please help me understand this. Thanks!

Quote:

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Originally Posted by SilverBullet75

Interesting...
In my mind, if the tire is rotating 1.8% faster, and at speedo 60, true speed is 58, wouldn't that mean that the ODO mileage is off by a bit... should be less than 411... which would mean that the MPG should be lower instead of higher. ??

I'm in no way a mathematician... actually, I suck at math. So, please help me understand this. Thanks!

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no, I think it's when the ODO shows 60 mph, your ACTUAL speed is higher, so we're in danger of speeding and not knowing it...a bad idea around the cameras in AZ! I did mine with my GPS unit and found at 60 mph on ODO I was actually going 66 mph, that's with my 285/60-18s.

yup, kat is right... if your speedo says 60mph then your going faster than that. your factory mph sensor is on the transmission. so if you add more diameter your going to go farther per rotation.

i always REALLY exaggerate these things to make them make sence. for example. if you put monster truck wheels on your VX, even when your VX said you went 1 mile, you would of gone more like 5 miles. so your moving at a faster rate. similar, if you put go-kart wheels on it, your would barely move at 10 mph on your speedo.

silverbullet, your right, it is backwards..

your tires are smaller than factory.. most everyone else is doing adjustments for larger tires, thats why it seems backwards to you

Thanks Etlsport! Thought I was going nuts! (not ruling that out though) :)

So, with that said, what sould i multiply by to get my true MPG?

By my calculation you actually got 18.96~ 19 MPG. You ODO is only slighty off and remember to use the % difference in the total miles travelled rather than the MPG. In other words you went 7.4 miles less than the ODO read.

My interstate tripped just yielded 16.6 MPG... not too bad with big tires a heavy foot

Put on 'Dweeb' hat

The circumference of your tire is the distance that your car will travel in one revolution of the tire. You can measure that by wrapping a tape measure around the tire ... or use the formula pi*radius. Radius is half of the tire diameter.

Nobody is going to go out and measure their tire circumference (probably not even their radius). They'll just use the advertised number. All you really need to remember is that the circumference is directly proportional to the diameter.

Since your speedometer & odometer are both just reading rotations of the tire, all you need to know is that if you switched to tires that are 10% larger in diameter than stock, you will be traveling farther & faster by 10% than your speedo & odo are registering.

One other thing to keep in mind is that during the life of your tires, the radius will continue to shrink (not that much on passenger car tires with a mild tread but significant in MTs and ATs). My Wrangler MTs measured 33" when new but are probably only 32" now that they are at the end of their life just due to tread wear.

Take off 'Dweeb' hat.

My VX would still get 10mpg if I got out and pushed it 200 miles.

I am surprised with my STi though. I am managing almost 28mpg in that. Well, I was before the weather srtarted to cool off here, Now It's getting about 23mpg. :\