Mpg @ 80mph

planning to take family to LEGOLAND, its a 2K round trip mostly at cali speeds of 78-80MPH the entire way. since Oregon still has a snail pace 55mph speed limit I really do not know how well our TDI's do at higher speeds in regards to MPG? What can I expect at these higher speeds? 2013 with a DSG? Reason I ask is because I just bought the wifey a Highlander Hybrid that manages 25MPG highway and it has more room for her junk but drives like a shopping cart full of bowling balls

Depending on topography, I would predict, fully loaded, upper 30s, low 40s. These cars are reasonably aerodynamic, but mpgs drop dramatically above 70mph, in my experience. They're also susceptible to crosswinds...mildly annoying.
You've probably read here that some (myself included), in a quest for higher MPG, raise tire PSI above 40psi, but these cars can get a little squirrelly, and again, in my experience, will "tramline" a bit. Nothing dangerous, but enough to require your attention. I finally settled on 38psi (Conti Pro or Pure Contact, can't remember which).
Enjoy your trip!

My 2012 6 speed with stage 3.5 always averaged about 38mpg at 80 on my 220 mile commute with very spirited driving. My main winter vehicle now that's its gone is a 81 rabbit pickup with the 1.6 diesel and man does it struggle on the hills lol. To the floor most of the way between 72-80. Still getting about 38mpg lol!

Wind resistance as a function of speed is a concern with any vehicle. And even if the vehicle is ærodynamic, the wind resistance still increases in a non-linear fashion* as speed increases.
Somewhere in this forum, someone has posted a graph of this function, and around 60 mph is where it starts to get serious.

*Observe the graph in the second post in the linked thread. http://www.bikeradar.com/forums/viewtopic.php?p=15452850

Rico567 said:

Wind resistance as a function of speed is a concern with any vehicle. And even if the vehicle is ærodynamic, the wind resistance still increases logarithmically* as speed increases.
Somewhere in this forum, someone has posted a graph of this function, and around 60 mph is where it starts to get serious.

*Observe the graph in the second post in the linked thread. http://www.bikeradar.com/forums/viewtopic.php?p=15452850

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I haven't studied math/algebra/trig since high school (uhh...yeah...with a killer slide rule!!!), but...didn't you mean to say "exponentially"?

Our stock 2012 gets about 38 MPG at 80 MPH.

Mine gets 38 in the summer but down to 32-34 in the winter at 80mph

tdiatlast said:

I haven't studied math/algebra/trig since high school (uhh...yeah...with a killer slide rule!!!), but...didn't you mean to say "exponentially"?

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The two terms are the inverse of each other; the point is that wind resistance as a function of speed isn't linear, and the power/fuel required to go 1 mph faster at some speed will increase at a greater rate (exponentially -if you will- e.g, 1,2,4,8,16) than the arithmetic (linear, e.g. 1,2,3,4.5) increase in speed. And "ærodynamic" vehicles don't get a free pass from this, they simply achieve incremental improvements in efficiency. At some speed, under these conditions, the air could be thought of as a solid.
I have edited my original post with a suitably neutral (although more verbose) expression.

"non-linear" is a perfect description. Thanks for the clarification.

Coming to visit the land of the nice I see. My 03 5spd going to Colorado this year at 75-80mph was around 44mpg. At slower speeds I see closer to 50mpg. Not super relevant to your common rail, but I would guess you will only loose a few mpg. The main factor is wind resistance. The engine running at a higher rpm does not make much of a difference its how much work it has to do that does in terms of mpg.

wife really wants to drive the Highlander and its only about $150 in fuel more- plus I can sleep in the 3rd row (as long as she doesn't wreck) after I get tired. Bought the NMS for this type of trip and to cheat on it with a SUV seems wrong

With the kids and all I could see why you'd want the highlander. I have a lot of difficulty sleeping when my wife is driving though. Over 30+ years there have been several times I have been awakened to have to grab the wheel for an emergency. She does better these days but......

I get over 40 mpg at about 77 mph here I believe. With all the weight though You might get less.

My cruising speed is probably around 75 Mph on cruise control. There is NO way I get into the 50 Mpg area. Closer to 41 US Mpg over the last 1 1/2 years. I record every fill-up religiously.
My opinion is people claiming 50 Mpg at 80 Mph are either dreamers or are stretching the truth and do not know how to correctly calculate Mpg.

BTW: My mileage figures of 50.71 are using Imperial gallons, deduct 20% for US gallons.

Jetta_Pilot said:

My cruising speed is probably around 75 Mph on cruise control. There is NO way I get into the 50 Mpg area. Closer to 41 US Mpg over the last 1 1/2 years. I record every fill-up religiously.
My opinion is people claiming 50 Mpg at 80 Mph are either dreamers or are stretching the truth and do not know how to correctly calculate Mpg.

BTW: My mileage figures of 50.71 are using Imperial gallons, deduct 20% for US gallons.

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I agree with this post. Most of the miles on our '13 Passat are at 75 mph with the cruise set, and as you can see from my fuelly average*, it's very close to what you're getting— and close to the overall Fuelly average for this type of vehicle. So, unless some sort of "hypermiling" techniques are used (and going 80 mph isn't!), there's no way anyone's getting 50 miles per US gallon at that speed, not without one heck of a tailwind.

*Note: The Fuelly average on our car has been compiled on all fillups since new in July '13 (car now at 67,8XX), and strictly with pencil and paper, no MFI figures used.

Funny you should post this Q:
I was thinking about yesterday's trip / mpg:
Last week I replaced my beloved 2012 Passat TDI SE (Buyback) with a like new 2015 Passat TDI SEL. I got through the gantlet of vehicle logistics, and was required to take my first round trip from Fort Lauderdale to Jacksonville yesterday.
The tank on the way up skewed by local driving, so on the way back from Jax, I filled up before hitting the highway. The temperature was cool, so 2/3 of the trip had only the vent on. I did drive with haste, with cruise set for 80 mph most of the returned trip.
I filled up immediately after exiting I-95.
Actual:
307 miles
8.068 gallons
38.05 MPG
MFD Info:
43.6 MPG
306 miles
73 MPH Avg Speed
4:12 HH:MM
My partner in my business has the. same vehicle, and he claims that driving at 72 with cruise, gets him 42 mpg. I suspect that is a MFD number. (Which is usually optimistic in my experience)
On my soon to be bought back 2012, I once took a drive to / from Key West. The interesting fact about US-1 in the keys is that you can't speed. If you do, you will get a ticket. So it's a forced drive at 45 to 50 mph. That trip was the record holder at 51.6 mpg.
MFD Info:
52.7 mpg
229 miles
40 mph
5:40 HH:MM

jrm said:

planning to take family to LEGOLAND, its a 2K round trip mostly at cali speeds of 78-80MPH the entire way. since Oregon still has a snail pace 55mph speed limit I really do not know how well our TDI's do at higher speeds in regards to MPG? What can I expect at these higher speeds? 2013 with a DSG? Reason I ask is because I just bought the wifey a Highlander Hybrid that manages 25MPG highway and it has more room for her junk but drives like a shopping cart full of bowling balls

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Am I the only one who doesn't know where Legoland is? And why aren't you flying? It's hard to beat the cost of flying, even with a family, when you take meals and hotels into account.

I know there is one a few minutes away from me in Winter Haven, Florida, but from CA or Oregon it is definitely more than 2k miles. I assume there is one somewhere on the west coast.

LegoLand, near San Diego, was the first in the states, 1999 I believe. Florida was opened 2011.

yup, southern cali-80F temps! its 1,100 miles one way- driving the TDI will save us $1500 in Airfare and shuttle services as we plan to hit up Disanyland and universal studios as well. I plan do drive strait threw, wife can fall asleep in southern Oregon and wake up in the hotel parking lot- don't worry i'v done it before as I won a 15kw diesel generator in a military auction 2 years ago and had to drive to the Mojave dessert (yermo yard) to pick it up only to turn around and drive strait back home over my weekend days off, that one was rough so only one way should be ok
PS Folks over on Toyotanation think my Highlander Hybrid will get 22-24MPG, granted it does idle down to a mind blowing 900 RPM when up at 75MPH on flat ground! that ECVT is pretty crazy stuff! Goes between Generator mode on flats and direct drive on the hills, made the wife drive while I monitored it with torque

I'd take the vehicle your family will find most comfortable. Fuel savings won't cover much of Disney admission, anyway.

Interesting, 20 years ago I drove my family all over the east coast in our supercharged Toyota Previa. That car got 24-26 MPG running at 80. Much simpler vehicle, 4 speed transmission. Perhaps we haven't made a lot of progress when it comes to FE.

IndigoBlueWagon said:

I'd take the vehicle your family will find most comfortable. Fuel savings won't cover much of Disney admission, anyway.

Interesting, 20 years ago I drove my family all over the east coast in our supercharged Toyota Previa. That car got 24-26 MPG running at 80. Much simpler vehicle, 4 speed transmission. Perhaps we haven't made a lot of progress when it comes to FE.

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In an analogous example, our second vehicle is an '04 SAAB 9-5 wagon that will be 15 model years old this year. It has a 2.3 liter turbocharged four and a 5-speed manual. With around 195,000 on the clock, gets 24-25 mpg in town and 30-31 mpg on the Interstate at 75 mph. Many of the non-hybrid cars we would be looking at today to replace our '13 Passat TDI wouldn't do much better, and some can't match it.
We bought the Passat (our first diesel) to get increased fuel efficiency, now we're pretty much back where we started in 2013 when it comes to car shopping......

Rico567 said:

We bought the Passat (our first diesel) to get increased fuel efficiency, now we're pretty much back where we started in 2013 when it comes to car shopping......

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Snag a '15 TDI and be happy to motor on for another 5-8 years.

I drove a 93 Volvo 960 5 door, got 25mpg on the highway but around 11mpg around town. Traded it for the 2010 jetta, replaced the jetta with the Alltrack and manage to get around 28-30mpg on the highway, but the Alltrack is much smaller car with less power. two steps forward one step back.

I risked a ticket and took the Highlander up to that speed in a rural area, and man- I heavily vote for the Passat as the Highlander wasn't fun at all where as the Passat is for sure a Highway drivers car at those speeds as it is solid and precise! Half the drive (Shasta to Eugene) is threw tight twisty interstate with only inches to each concrete divider plus deep stud ruts, Time to use VCDS to code high beam + low beam + fogs on all at once

Report on the MPGs of the trip!

Drive safe and have a great time. fwiw I would have taken the Passat also.

My fuelly, granted it only covers 3K miles, shows how my car is performing on my normal commute. At least 60% of my miles are at 80 mph on I-17 between Flagstaff and Phoenix, the rest is driving around Phoenix. The DSG is geared a little shorter prior to 2015, but I’d expect around 40 mpg.

Whatever cost savings you think you are going to make is going to get blown out of the water the first time you pay for lunch at legoland =]

So Toyotanation flagged my post in the Highlander Hybrid thread about breaking a forum rule about street racing and exceeding the speed limit, seriously got me laughing! In the HYBRID thread! Good stuff over that way, anyways I'll have a Cooler in the trunk I'm not cheap, just wise the only thing is the Passat is singing at 2400 RPM while the Highlander is down around 1200 RPM. Hmm, one wouldn't think a diesel would be geared this short as bronco stated

You could explain to the humorless mods at TN that your scenic route from Oregon to Legoland will take you through Idaho and Nevada, where maximum posted speeds on rural Interstates is 80 mph.... lol

http://www.iihs.org/iihs/topics/laws/speedlimits/mapmaxspeedonruralinterstates?topicName=Speed

Don't forget your training session on how to use a gas pump!