Let's walk through this. Keep in mind that your actual mpg will vary based on multiple things such as driving habits, and environmental factors, so YMMV (no pun intended)

In your example above, you have established several facts outlined below:

$1,000 Total Modification Cost
$4 Cost Per Gallon
20 Current MPG
22 MPG after mod (+2mpg)

To figure out your savings, you need to figure out your Cost Per Mile. We do this by taking your Cost Per Gallon, and dividing it by your MPG:

$4/20 = $.20 Cost Per Mile

Next, figure out the Cost Per Mile with the mod.

$4/22 = ~$.18 Cost Per Mile

Now that we have those figures, we can calculate the savings from the mod, on a per mile basis. In this case, you are saving $.02 per mile

$.20 - $.18 = $.02

So, now we know that every mile you drive with the mod will be $.02 cheaper than it currently is. The next step is to figure out how many miles you need to drive before the savings equal your cost. This is your Break Even Point. We do this by dividing the cost by the savings. In this case, your cost is $1,000, and you are saving $.02/mile.

$1,000/$.02 = 50,000 Break Even Mileage

To figure out how much money you save over a given mileage, simple multiply the miles driven by the savings. We'll use your 200,000 in this case.

200,000*$.02 = $4,000 Savings over 200,000 miles.

Therefore, if you drive 200,000 miles after the install, you save $4,000. After your $1,000 cost, your net savings are $3,000. However, be advised this is simplified, as it assumes gas will be $4/gal for the entire 200,000 miles, and that you're getting constant MPG.











Now, I'd like someone to tell me how you guys are getting such high mileage. I've been getting 13-14 the past couple months.

 

Good thinking!
You might notice after my first post i did some thinking. in my 2nd post I figured 2 mpg gain was 10 % of 20 so it would be 20000 free miles out of 200000,at 20 mpg it would be 1000 gal at 4 $=4000$ or 1000$ in 50000!! Same result,different methode!

 

For me, I want to maintain my mpg, and strengthen my truck as I plan on keeping it for a long while. For me, as a daily driver, I want some specific off-road mods and I know I need to do some mods for the performance side of things. Im looking for a bit more kick in my engine ( torque and hp).. but not at the cost of all my mpg.

Please continue to post any suggestions... thanks.

 

A couple of folks have installed a header and gotten 10-30 hp out of that. A couple more HP might help drag the H3 down the hwy at 65+ and help out with fuel economy since you don't need to be in the gas as much.

Ditch your roof rack if you have one, same for the cross bars. Remove the extra weight you don't need for the highway, if you're not wheeling but once a year or never then you don't need to have it on weighing you down and increasing weight.

Use an electric fan. You will get back about 5-10 hp from that and lose a lot of rotating mass from the engine crank.

Get a tune up and use fresh synthetic fluids all around. Clean your throttle body and intake and look into a ported throttle body for more power/response to keep your foot out of the gas as much going up hills or on the highway.

Get lighter, smaller, fuel efficient tires like a set of 32" Road Venture HT tires. Keep them properly inflated.

The last thing would be to get a ScanGauge or similar to monitor your mileage and driving habits to "teach" you how to drive more efficiently. No drag race starts, no on/off the gas on the highway or down the street and learn to anticipate stops and roll into them versus locking up the brakes coming up to every stop sign.

Everything else is pretty much snake oil or not gonna improve much on your driving experience. That Flowmast might sound nice and have shiny chrome tips and putting K&N stickers on your back window might look cool but actual improvements are negligeable.

 

I too have hit that magic mark of 21+ MPG, highway only, of course.
I have an 07 adventure 5-SPD with just Doc's CAI kit and a MUTAINT recommended AFE PRO Dry S air filter.
This truck is more than capable enough for my off roading an I don't want to diminish that highway mileage

 

Removing dead weight will net you some MPG without spending much $$$.

 

I have an 06 with 142,000 miles and got an average of 21 MPG for about 700 miles last year. Haven't seen that number since.

I have the Air Doc and Spectre filter. I drove 65-70 MPH most of the way.

I'm making the same trip this year and am curious if I can get the same.

 

I have hit almost 100 MPG.

Of course it was descending into the Sequatchie Valley in neutral - and it only lasted for 4 miles. But for those 4 miles it was glorious.

 

Haha! Bflank, I got you beat! I was coasting downhill on the highway around 75 once for about a mile long stretch and the ScanGauge went to 99999 and then 'tilt'. bwuhaha

 

Lol! You guys are hilarious !!!