MPG loss after lift, bigger tires, and other outfitting.

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Dharma Dude

Dharma Dude

Joined
Nov 15, 2016
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Location
Palo Alto, California & Squamish, British Columbia
What are poeple's experience with MPG losses after mods: lift, regearing to 4.56 bigger tires (34), and heavy mods like bumpers?

Is it realistic to think that I'll go from 18 to 15 on the highway cruising between 65-75 after mods? I'm getting 18-20 stock.
 
I still get 15 highway on 35s with 4.56 if I drive the speed limit (IF!!!)
 
Also, with bigger tires you'll be going faster/farther than you speedometer/odometer will show. So you you'll need to calc that in to your mpg estimation.
 
Thanks everybody for the great info.

billmc said:
Also, with bigger tires you'll be going faster/farther than you speedometer/odometer will show. So you you'll need to calc that in to your mpg estimation.
Click to expand...

Yes, I'm talking about *true* mpg as measured after tire adjustment, or odometer readings/gas receipts.

GXO said:
I still get 15 highway on 35s with 4.56 if I drive the speed limit (IF!!!)
Click to expand...

So I assume also that Dan's 15 is after adjusting for tires/gearing. Is that correct?
 
I get 14-15mpg bone stock. Haha.
 
My 15 is GPS based, not speedo. Accurate. If I go 5 mph over 65 I lose a ton lol.
 
billmc said:
Also, with bigger tires you'll be going faster/farther than you speedometer/odometer will show. So you you'll need to calc that in to your mpg estimation.
Click to expand...

With 4.56's and 34's he'll actually be going slower/less distance, but yes - proper math will be different than what the computer shows.
 
I lost 1.5 mpg with lift and true 34's, no other mods. Getting around 15.5 to 16.5 GPS calculated depending on mood that day, and where I am driving.

Jeremy
 
How do you guys determine GPS mpg, did you divide GPS miles by gallon fill-ups from receipts? Or was it just kind of a guestimate?

Prophecy said:
I lost 1.5 mpg with lift and true 34's, no other mods. Getting around 15.5 to 16.5 GPS calculated depending on mood that day, and where I am driving.

Jeremy
Click to expand...

This is very encouraging! Cool. BTW what kind of lift did you get and the actual tire size? Did you have to cut/grind alot to get things to fit?
 
I created a spreadsheet to track. I get the receipt for each fillup (or write down details), spreadsheet automatically calculates actual miles due to tire size difference (odometer miles since last fillup X 1.1 or whatever # is correct for you; divided by gallons added).

I use this spreadsheet to track everything, actually - date, odo miles, corrected miles, gallons, mpg for last tank, mpg since I started; cost, grade, running cost; maintenance and modifications. I've had the GX for 3 years now and running mpg for that period is 16.5, at a total cost of $6542.69. Grade of fuel hasn't shown any difference whatsoever in mpg.

I did this for my 80 for the 8 years I had it, the guy who bought it from me really appreciated it and has kept it going.
 
I just use a GPS trip tracker on my ipad that is mounted in the truck. When I fill up, I look at the GPS total and do the simple math.

Math is hard :P
 
little_joe said:
I created a spreadsheet to track. I get the receipt for each fillup (or write down details), spreadsheet automatically calculates actual miles due to tire size difference (odometer miles since last fillup X 1.1 or whatever # is correct for you; divided by gallons added).

I use this spreadsheet to track everything, actually - date, odo miles, corrected miles, gallons, mpg for last tank, mpg since I started; cost, grade, running cost; maintenance and modifications. I've had the GX for 3 years now and running mpg for that period is 16.5, at a total cost of $6542.69. Grade of fuel hasn't shown any difference whatsoever in mpg.

I did this for my 80 for the 8 years I had it, the guy who bought it from me really appreciated it and has kept it going.
Click to expand...

I've run the same thing for many years, except that it was a LAMP server with a postgresql backend. Makes it much easier to maintain 8-9 vehicles.
 
billmc said:
I've run the same thing for many years, except that it was a LAMP server with a postgresql backend. Makes it much easier to maintain 8-9 vehicles.
Click to expand...

That's so 2000!:p:)

This decade, you add an OBD reader paired with a GPS unit feeding a LTE modem that uploads mpg and miles data real-time to a cloud app on AWS or Google. Then you can do 1-10 million cars.

Oh wait,....that's what Tesla did.

Anyway....enough geeking out.
 
I have a Kenwood DNX893s and it tracks my MPG, I enter the gallons and it tells me the MPG bases off the GPS miles. Also have "Gas Cubby" but it doesn't adjust for the larger tires. Gas Cubby says I have avg 15.1 over the last 30K miles, so add in the adjusted tire size and its about 15.8. Best was 22mpg, worst was 11mpg (off road for 200 miles). Funny thing is that the GX computer calculate MPG is almost right on now.
 
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NMBruce said:
I have a Kenwood DNX893s and it tracks my MPG, I enter the gallons and it tells me the MPG bases off the GPS miles. Also have "Gas Cubby" but it doesn't adjust for the larger tires. Gas Cubby says I have avg 15.1 over the last 30K miles, so add in the adjusted tire size and its about 15.8.
Click to expand...

What size tires and gearing are you running? Do you have heavy bumpers, front and/or rear?
 
stock bumpers, RCI metal full set of skid plates, stock gears, Dick Cepek 265/75/17 which are 32" tall tires and 10.7 wide, FUN COUNTRY | DICK CEPEK TIRES AND WHEELS I have a storage box in back and now a ARB 50qt fridge.


the Kenwood says 15.9 since last June. this shows my best at 28mpg, but I missed a top off in there.

IMG_0306.webp
 
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Dharma Dude said:
That's so 2000!:p:)

This decade, you add an OBD reader paired with a GPS unit feeding a LTE modem that uploads mpg and miles data real-time to a cloud app on AWS or Google. Then you can do 1-10 million cars.

Oh wait,....that's what Tesla did.

Anyway....enough geeking out.
Click to expand...

Well, I'm so last century. I never even drove a car made this century until I bought the GX used in 2012! :D
Anyway, I've been in IT for 30 years, and refuse to do Cloud or google anything. LOL
 
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