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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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a.k.a. porkchopzz4
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890 Posts
callisto9 said:
is this the best way to figure MPG?

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?
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.
 

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Diesel Inside
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Yeah...that's a pretty complicated way to describe it...but to calculate fuel economy it takes 2 fillups. Make sure you fillup to the same spot each time (more important for diesel owners...not so much for gas). Take the # of miles you used for that tank and divide it by the # of gallons you filled up with for tank 2.

1 - Fill up car to the top, reset trip-o-meter
2 - Drive car
3 - Fill up car
4 - Divide miles on trip-o-meter by # of gallons

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.

Anyway...good luck.
 

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Good-bye Curby...
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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...
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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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a.k.a. porkchopzz4
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callisto9 said:
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. :(
Half of my commute is interstate and I do 80-85.. and I get just shy of 26 mpg. I suck! :)
 

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Premium Member
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4,319 Posts
When I had my Miata I would hang out on www.miata.net. I constantly saw people bragging about what great milage they were getting in thier cars.

The Miata (at that time atleast) was usually a second or third car and therefore driven mostly in traffic free environs and often on back roads by most people. I drove mine daily and had a 22 mile commute with lots of stop and go traffic.

They claimed to be seeing 30mpg on a regular basis and as high as 37mpg on road trips. I struggled to see better than 26mpg.

That was untill we decided to take the back roads all the way down to Tennesee from Cleveland. My average speed dropped from the mid 80s and low 90s to around 50mph. My gas milage went thru the roof. I went from 26mpg to 38mpg on that trip. I was flat out amazed.

I'm not an idiot and understand that higher rpms and aerodynamics play a big part of the fuel economy game but even though I knew that, I was still stunned to see that it made that big of a difference. That being said, to me its just not worth the extra mpgs to be bored stiff on the highway by setting my cruise at 60mph. I like to drive fast and am satisfied with my mpgs.
 

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Diesel Inside
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359 Posts
Fowvay said:
I'm not an idiot and understand that higher rpms and aerodynamics play a big part of the fuel economy game but even though I knew that, I was still stunned to see that it made that big of a difference. That being said, to me its just not worth the extra mpgs to be bored stiff on the highway by setting my cruise at 60mph. I like to drive fast and am satisfied with my mpgs.
No offense to you at all...but I believe this is the mentality of most people which is why manufacturers couldn't care less about efficiency. We still get sold on the driving experience and all the things we could do with that SUV. But we complain like all get out when the gas price jumps. :rolleyes:

Sorry... /rant

I'm loving my TDI and my 45mpg driving it however I want. So no complaining here.
 

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Premium Member
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4,319 Posts
jpdeuce said:
No offense to you at all...but I believe this is the mentality of most people which is why manufacturers couldn't care less about efficiency. We still get sold on the driving experience and all the things we could do with that SUV. But we complain like all get out when the gas price jumps. :rolleyes:

Sorry... /rant

I'm loving my TDI and my 45mpg driving it however I want. So no complaining here.

I get between 28 and 29 mpg setting my cruise at 85mph. I'm pretty darn happy with those numbers.

I am a huge diesel fan as well and love playing the high mpg game in them but I also like to have a car where I can drive like I want, have all the power to spare for doing some serious passing etc. I'm tickled pink to have a car with 229hp & 275lb/ft torque that still gets nearly 30mpg on the highway. I have always favored cars that get big MPGs and still provide me with a fun driving expierence. I guess thats why I love VW's so much. :D

I'm hoping to add a TDi to our ever growing stable in the not too distant future (summer 2006). I really miss being able to brag about those crazy MPGs, but after having some real bhps underfoot. I don't think I can give up my plaything either. So I guess I will just have to own more than one New Beetle. :D

Tom aka Fowvay
 
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