"Gen 2" Dodge Durango mod's question

tmw4i

Registered
I've finally got around to modifying my '04 Durango with 20" wheels and tires (up from 17"), and a custom Cat back exhaust. Since the mod's, I've noticed my all around gas mileage dropping from 11 mpg to 9 mpg. My driving is the same as before. What gives???
 
RE: "Gen 2" Dodge Durango mod's question

increased rotational inertia of those aftermarket wheels means slower acceleration and longer stopping distances. slower acceleration means you're into the gas more, costing you mileage. The exhaust probably didn't make much of a difference.
 
RE: "Gen 2" Dodge Durango mod's question

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increased rotational inertia of those aftermarket wheels means slower acceleration and longer stopping distances. slower acceleration means you're into the gas more, costing you mileage. The exhaust probably didn't make much of a difference.
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Any suggestions on how to increase a few more mpg's, given the current state of my vehicle?
 
RE: "Gen 2" Dodge Durango mod's question

Drive slower.

Honestly, if you can come up with a good way to increase MPG on an SUV, i'm all ears. I'm lucky if i can pull 12 out of my suburban, and i do mostly highway driving.

Make sure the vehicle is properly tuned up, also.

How are you calculating MPG? If you put larger wheels/tires on (larger overall rolling diameter) and didn't re-calibrate your speedometer, you're getting better MPG than you think you are.
 
RE: "Gen 2" Dodge Durango mod's question

My PSD F250 calculated highway mileage went up about 10% from 13 mpg to 14.5 mpg when I installed a 5" turbo-back open exhaust(no muffler).
 
RE: "Gen 2" Dodge Durango mod's question

[div class="dcquote"][strong]Quote[/strong]
How are you calculating MPG? If you put larger wheels/tires on (larger overall rolling diameter) and didn't re-calibrate your speedometer, you're getting better MPG than you think you are.
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My Durango has an electronic mpg calculator in the overhead console. It tells me that I'm getting 9 mpg. I think I will be testing to see if accurate by doing the calculations manually for a few fill up's!
 
RE: "Gen 2" Dodge Durango mod's question

if your speedo is off because of the larger wheels, you're manual calculations will likely be off too. It would be a good idea to either have a friend with stock gears and wheels pace you to get an idea if it is off, or use a GPS.
 
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