My Car Is Getting 56MPG But Shouldnt???

Last month I managed a 56mpg average for the month while doing almost 2,000 miles total... Which is pretty consistent with my usual mileage give or take 2-3 mpg.

After reading threads and seeing how people who manage 50+mpg tend to baby the car, not go fast on the highway, accelerate at a steady pace, and so on. It got me thinking....

On the highway if traffic allows it I tend to cruise between 70 and 80, sometimes 85 depending on the limit. When I come off a light, I don’t baby it to the speed limit at all. I shift at about 3K, and cruise around town at or about 2K.
I also love my exhaust note, so I do floor it when I can.

I fill up at the same place, once it clicks I will wait a seconds, let it reclick and then fill it to the nearest dollar, or half dollar depending on how far each is.
This is very consistent, and 50 cents worth of fuel should not make a noticeable impact.

My driving route is pretty much the same time after time. I rarely ever change it, unless I am very late for work and I-66 is no longer HOV only inside the beltway.

Modification Wise...
I have a Euro R32 bumper and I am sure it’s not as Aerodynamic as the stock one that came with my car. However, the license plate is either not on the car or molded to the bumpers shape. A freedom design rear wing, side skirts, and a rear apron...

I have high performance tires (225/45R17) all around, with 22lb rims. Combined they are about 40 lb's per wheel because the tires have less then 1/2 thread on them. Tire pressure wise, I used to run nearly 50psi, and now I run mid 30's, the diff in MPG I can’t really tell lol.

Engine wise I have RC3, a custom CAI, 2.25" catback straight, malleted injection pump, egr delete, and a few minor things. But, my intake mani has some buildup.

Is there something I am missing?
I don’t think my car should be getting this mileage, especially on B20.

Im going to fill up on friday night, so I have a full tank when I go to Show-N-Go, Ill do my first October Calculation then

I'll trade cars with you!

I fill up at the same place, once it clicks I will wait a seconds, let it reclick and then fill it to the nearest dollar, or half dollar depending on how far each is.
This is very consistent, and 50 cents worth of fuel should not make a noticeable impact.

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Not really accurate as pumps click off at different times amd different grades of diesel with varying additives may tend to foam less/more causing the pumps to shut off at different levels during fillups. If you want consistancy, try searching for "venting" or "ventectomy" and follow the directions. This way you'll be filling up "to the brim" on each and every fill up no matter what station or what pump. Added bonus is that you'll likely extend your range between fillups!

Other than that, your numbers are very good (taking into consideration a small correction factor) and you should be happy you got one of the "good" cars!

I do have my tank vented, I just dont have patience to fill it to the brim lol.
Cool! Wido is a "good car" hehe.
Ill fill it to the brim this weekend and see if I can make it to jersey without leaving the first mark of the tank lol.

So VW made everyones car differently?

__. Only 56 MPG??? What are you doing wrong?
'

If you are "busting" 70 MPH and "cruising" at 75 and hitting 85 MPH from time-to-time, you are not getting 56 MPG.

With the tire/wheel set-up you have, is your odometer correct? Yes, 50 cents will make a difference. And, if you are not completely filling-up...... then it "ain't" accurate!

Also, if you are driving in "that" Manassas traffic, well, I have and I know how it is....... I sincerely doubt the numbers you are getting!

I know my odo is slightly off, but I doubt that much.

I dont see much traffic at all. I work in Arlington, and for the most part I leave at 8-8:30 from my house and by the time I get to I-66 I dont see much traffic. I come home at 8pm, and again dont see much if any traffic. I have school in the early afternoon, and dont see traffic. So I am rarely ever stuck in bumper to bumper.
The morning comute is the worst where I cruise at lower speeds, but for the most part at night I am in the 70mph range if not higher. Twice I week I do about 115 miles at 80-85.

My math is bad, but not horrible enough to where I cant divide the number of miles on my tripometer by the number of gallons I dumped in.
Ill do a to the brim fill up and see how that goes with the numbers.

Better yet, get an average of at least three tanks. Five would be better. This evens out any irregularites.

That and prune juice.

I have one tank at 55 mpg. The rest are on average above 50 mpg. The lowest was 43 mpg and I was doing some heavy foot. The 116k miles I have driven my Jetta it has averaged over 50 mpg. When I push it past 70 mph the fuel economy begins to drop off. Its been a while since I done a road trip. But, my tank to tank fill-ups involve about 80% to 85% road miles. The balance is county roads and very little "city." I vent to the top every fill-up.

The 50 PSI tires should help your milage considerably....

I have been on I-66 in the bumper to bumper traffic and it can be awful on fuel economy. Sounds as if your commute is about right for superb milage...... hang in there and check it close.

hey I averaged 56mpg going to Florida from Massachusetts in febuary with my cruise set at 79mph tottaly stock 03 wagon.

My average was for a few tanks, 2000 miles worth of tanks lol.
Ill continue to do the math each fillup. Ill know another number this friday night

Tell me about it. A few months back I would start work at 8ish, I would leave the house at 6:30, and the morning traffic drove me up the wall! So now I start work way later, to avoid most of the traffic. Of course, all it still takes is a car on the side of the road with a hood open for everyone to slow down, but its not as slow, and people dont seem to slam on the brakes.

Back when speedtuning majorly f*cked up the car, I would be very happy to hit the mid 40's after driving carefully lol. Ever since Jeff did my car, my mileage has been that good.

How many miles on your Wagon?

My average was for a few tanks, 2000 miles worth of tanks lol.

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Just for clarification, did you figure your mileage on each tank, then average those numbers, or take the total miles traveled and the total fuel used and did the division using those numbers?

have you done a lifetime average? or at least start over and start a new lifetime avg? i have a hard time imagining these numbers at the speeds and conditions you say you drive in. i've kept track of every gallon i put in, lifetime at 15k miles is 44 for my PD (prolly about 60-70% highway). granted not totally broken in, but still.... i drive my fair share of 75+. lots of 45-60 and lots of 75-80mph zones where i drive. i'd say i avg 70-75 on the highway overall.

I did it for each tank.
How do I do a lifetime average?

I did it for each tank.
How do I do a lifetime average?

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Same way you do a single tank, except use total miles divided by total fuel used.

Hmm, I did out the math -- tire diameter + 2 * (width*aspect ratio / 25.4) and got 24.98" diameter for 195/65R15s (which were stock for my car) and 24.97" diameter for the 225/45R17. So no change there. I forget on blocking off the egr, what that does to mpgs's--I want to say that it does increase it by a few, so that could be the cause.

Yes, your mileage is too good. I think you should do something immediately! Bring your tire pressure down to 5 PSI. Don't use 5th gear. Put a restrictor plate in your intake snorkel.

If you keep this up, you'll have all the folks with PD engines rioting in your front yard. I can just see your Jetta now... upside down and on fire. Don't let that happen!

I agree that a life-time or running average is the best way to keep accurate dibs on your TDI fuel economy. But, a complete "fill-up" at the pump each time is very important in the calculation process........the issue is basically this: It must be "full" and the following fill-up must be just that....a "fill-up." Then the last thing is an accurate odometer. Pretty simple math after that.

Also, if a clubber is on the net (here in the forum), obviously they are using a PC. So, they ought to learn how to use Excel or some other popular spreadsheet program. I have 99.99999999% of all expenses on my TDI in Excel Spreadsheet. I fill my TDI to the top at each "fill-up." Therefore, I feel pretty confident in the numbers........ I do not believe there's a TDI that will "ring-up" 56 MPG cruising at 79 MPH........ bunk!

It seems no one can be happy here.

One has low mileage when they thinkit should be higher and one has high mileage and thinks it should be lower.

Nothing personal, I just thought it peculiar to see those two, one right after the other.

Okay!
I filled up to the click like usual and it stopped at: 8.25 Gallons, with only 462 miles on the tripo.

Then I proceeded to wait a minute, then slowly filled it almost to the brim., I did not want to spill any on my just waxed paint! The new total was 10.77 gallons. WHOA lol Thats over 2 gallons extra!

This week I did not go to the MD GTG's wich combined total about 200ish miles of 75-80mph driving.
I kept my speeds around 70mph.
So I think the pump is not consistant with the clicking. Because I managed 56mpg on this tank and me speeds were lower. However, I only dumped 8ish gallons with the click, where I usualy dump closer to 12ish.
So, from now on I will fill it to the brim!

If you are "busting" 70 MPH and "cruising" at 75 and hitting 85 MPH from time-to-time, you are not getting 56 MPG.

With the tire/wheel set-up you have, is your odometer correct? Yes, 50 cents will make a difference. And, if you are not completely filling-up...... then it "ain't" accurate!

Also, if you are driving in "that" Manassas traffic, well, I have and I know how it is....... I sincerely doubt the numbers you are getting!

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@ 75 to 85 mph on my trips accross the US I get around 50 on my Passat TDI . I checked the weight at Flying J on the scales at the beginning of my trip after I filled up . "3995 lbs " , drove 75 to 90 mph on the trip @ that weight and averaged 50 mpg flat for the whole trip in June .

I checked the weight at Flying J on the scales at the beginning of my trip after I filled up . "3995 lbs "

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Unless you're carrying four stout lumberjacks with you, there's no way to make a '97 Jetta weigh 3995lbs.

Mike

Who said anything about a Jetta , My car is a Passat .

And when I travel this drive there is just a little spot for me to sit in . The rest of the car is full up to the roof .

I have a life time and very consitient avg of 42 MPG.... I have kept records for about 20k miles. I usually drive anywhere from 75-90 mph... or stop and go traffic on the parking... err freeway during rush hour. I have gotten as high as 52mpg on a long 1000 mile drive where I kept the speed down to 70mph

And, that's not 56 mpg!

sorry i did'nt get back to you sooner i was in maine for a few days I've got 59k miles I had a guy up here do the egr mod and i think my mileage is even a little better now.

Trying to measure trip to trip mgp is erratic at best. The only mpg that really matters is the lifetime reading. It is nice to know what you are getting at times, but I wouldn't quote the figures if I was not sure of the accuracy. What does the first click of the pump mean. A splash of fuel to increase the pressure in the fill nozzle and click. Don't go by sounds. If you aren't topping it visibly, it isn't accurate.

On a trip, our 03 beetle manual can easily hit 55 mpg. "busting 75mph"
I get 52 or better if i use 100% dinodiesel on a day to day basis back and forth to work. my lifetime average at 25000 miles was 49.5. The mpgs have gone up since then on diesel. I now use b100 so the mpg have dropped some.

Hey you know i didd'nt even buy fuel on my trip untill south carolina almost 700 (695)miles and it took 12.5 gallons of fuel you do the math!!!!

The only mpg that really matters is the lifetime reading.

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59.4 mpUSg, thats over a lifetime of 78,075 miles in 3 years 9 months.

This car is amazing.