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Good-bye Curby...
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8,727 Posts
Discussion Starter · #1 ·
is this the best way to figure MPG?

To calculate fuel economy, start with a full tank; note the odometer (odometer #1) reading. Drive the vehicle normally and note the use mix (city, highway, or city-highway mixed). When the fuel gauge reaches approximately ¼, refill the tank and note the odometer (odometer #2) reading. Subtract odometer #1 from odometer #2; divide the result by the number of gallons purchased. One significant decimal place is sufficient. Examples: Odometer reads 30,455 when the tank is first filled. The vehicle is driven until the fuel gauge reads ¼ ; the odometer reads 30,723. It took 12.7 gallons to fill the tank again. Subtract the 30,455 from 30,723 and divide the result by the 12.7. [30,723 - 30,455 = 268] so [268 / 12.7 = 21.1 MPG]

also, i read this:

While each vehicle reaches its optimal fuel economy at a different speed (or range of speeds), gas mileage usually decreases rapidly at speeds above 60 mph. As a rule of thumb, you can assume that each 5 mph you drive over 60 mph is like paying an additional $0.21 per gallon for gas.

i did not know this. so, all those times i've been driving 78 mph on the highway, i've actually been hurting my fuel economy?
 

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Good-bye Curby...
Joined
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8,727 Posts
Discussion Starter · #4 ·
Porkchop said:
Yeah.. this is why there was a national speed limit of 55 mph through the 80's... because of the energy crisis. Oh lordy, I hope our illustrious legislators don't get that bright idea again.
so it's true? weird.

we just bumped our interstate mph up to 70 from 65 here in iowa. whereas before you could probably drive 75 - 80 mph and not worry, now they are busting people for driving 73 mph! they raised the speed limit, but they are really cracking down on people abiding by it!
 

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Good-bye Curby...
Joined
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8,727 Posts
Discussion Starter · #5 ·
jpdeuce said:
You are correct that speed kills your mpgs. 55 to 65 will get you the best mpgs...over 70 will really hurt ya. I set my cruise on 65 on the freeway.

The main killer of mpgs though are accelerations and idling. So if you can anticipate stops and keep your momentum going that will help you. If you can take roads where you will keep your speed up and have less stops and starts and lights...that will help as well.
ok, now something is clicking here. i just recently took a trip to des moines, IA (about 3 hours away) and the whole time my friend and i took turns driving. she drives about 80 mph and i drive about 75. when i calculated my MPG after that trip, it seems i actually got worse MPG on the highway than in town. maybe that's why. i need to slow the heck down. :(
 

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Good-bye Curby...
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8,727 Posts
Discussion Starter · #7 ·
Porkchop said:
Half of my commute is interstate and I do 80-85.. and I get just shy of 26 mpg. I suck! :)
i am getting 26 mpg in town! woot!
 
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