High speed MPG - (for thoes mostly near an autobahn...)

eddie_1

Veteran Member
Joined
Dec 27, 2004
Location
Hannover, Germany formerly Toronto & NY
TDI
Jetta Wagon 2003 TDI tuned to 170HP, A6 Wagon 2008 TDI 2.7L tuned to 340HP
I've been in Germany now for over a month. (Sorry for my delayed replies, I still don't have dsl at home yet) I haven't done any major measurements but I must say I don't see any really big change in mpg by driving fast. I switched my scangauge to metric so I have litres/100KMs. This is a good thing to do in any case because it stops fluctuating all over the place when set to mpg. (My mpg also improved going from RC3 to RC5.)

What I see on the scanguage is that when I am cruising at 80mph it shows 3.5L/100KMs, at 100mph 3.8L/100KMs and at 130mph 4.3L/100Kms. There is a slight increase obviously for the faster speed, but not enough to break the bank. (Obvioulsy there is more wind resistance but you are also clocking the kms in no time and cut short your travel time by half hour before you know it.) What I find that burns up fuel is the constant acceleration and braking. In that sense if you drive it like you stole it in the US on hwy, you have to constantly keep decelerating/braking because folks are moving into the left lane at 55mph when you are doing 90mph (ever driven in Florida? lol) or if you go far enough you get copped. Here the traffic really flows, most times the left lane is clear if there is not too much traffic. The end result is despite all the high speed driving I'm not seeing any overall mpg loss by driving in the >100mph speed range. I think I was burning more in Northeast due to different driving conditions. Of course in the midwest things would be different if you pulse and glide with nobody on the road, can't beat that.
 

Bob_Fout

Oil Wanker
Joined
Sep 5, 2004
Location
Indiana
TDI
2003 Jetta - Alaska Green (sold) / 2015 GTI 2.0T
You SG is very much out of whack.

3.5L/100km is 67 US MPG.
3.8L/100km is 62 US MPG
4.3L/100km is 55 US MPG
 

eddie_1

Veteran Member
Joined
Dec 27, 2004
Location
Hannover, Germany formerly Toronto & NY
TDI
Jetta Wagon 2003 TDI tuned to 170HP, A6 Wagon 2008 TDI 2.7L tuned to 340HP
You SG is very much out of whack.

3.5L/100km is 67 US MPG.
3.8L/100km is 62 US MPG
4.3L/100km is 55 US MPG
Those are instantaneous numbers I see on the gauge while driving at constant speed and at those speeds. It could be the SG is not calibrated a 100%, but I think the relative numbers (not absolute) are those that are interesting. I'm not jumping to 8L/100KMs or 10L/100KMs when cruising at 130mph.
 

eddie_1

Veteran Member
Joined
Dec 27, 2004
Location
Hannover, Germany formerly Toronto & NY
TDI
Jetta Wagon 2003 TDI tuned to 170HP, A6 Wagon 2008 TDI 2.7L tuned to 340HP
:)

There is absolutely no way that you are getting those kinds of true L/100km at those speeds!

:D

D
I'm not sure if the disconnect is that big. Here is rocketeer928's POST with RC5 and same mods more or less as I. He got 500 miles on half tank, albeit with ventectomy. When you look at his post and an instaneous reading on my scanguage I don't see the big disconnect. Plus that wasn't really the point of my post.
 

manual_tranny

Smyth Performance- Intern
Joined
Jan 5, 2010
Location
New Bedford, MA
TDI
2001 Golf @182K; 2000 Jetta @290K
I don't know guys, that Jetta wagon is pretty highly modified and Eddie was getting pretty good mpg at highway speeds here in the US before he left. The exact numbers are off, but what is relevant to the discussion is the percentage difference at high speeds- not much. If you will allow me to make a few assumptions, I think I can calculate a more realistic fuel consumption.
Eddie and I did his timing belt together and the locking tools fell into place at TDC. Jeff's RC5 tune with a 17/22 and a big FMIC is probably getting it's first look at 130mph sustained in a Jetta Wagon. Consider that a Jetta Wagon may be more fuel efficient than you expect at higher speeds because it is very long. Also remember, Eddie's car is one of the most meticulously maintained vehicles on the club.
From talking with Ed, I think I remember he told me he was usually getting 45-50mpg at 70-80mph. So, if we take the scangauge numbers and lower them by the percentage between the scangauge value and the expected value, we can get realistic estimates about fuel consumption at 130mph in a highly modified Jetta Wagon.
So actually these are very impressive numbers. I would conservatively estimate that Ed's Wagon gets 47mpg at 80mph. The difference between scangauge reported mpg and my predicted actual mpg is a hair less than 0.3 (30%)
With this 'guestimate' number, if I assume that the difference between scangauge consumption numbers stays constant (or at least relatively close) after calibration.
So "real" mpg is more likely to be:
80mph - 47mpg
100mph - 43.5mpg
130mph - 38.58mpg
Ed, I think we're going to need you to make multiple identical repeat trips down the autobahn at 130mph so that you can fill up again and again and confirm my numbers. ;)

P.S. $#^! man, I'm jealous!!
 
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DasTeknoViking

Veteran Member
Joined
Nov 7, 2010
Location
Palatine IL
TDI
B4 TDi, A4 R32
Off topic but you have a 6MT or taller 5th in that Wagon ? What about even faster ? Wondering what she will do and how well planted it feels. I know my R32 feels rock steady at 155+ compared to other cars I've driven.
 

Conan

Veteran Member
Joined
Dec 2, 2010
Location
Denver
TDI
2003 GLS TDI
I did a highway mileage test yesterday. Totally warmed up the car, drove on the highway for a while, filled up, and went about 360 miles without stopping. I know at one point I had a vicious headwind, and sometimes a strong crosswind, but it's hard to tell when you're on the freeway. Route (I-25 south of Denver) was fairly flat (for CO), and traffic wasn't a factor. I coasted in neutral on all the big downhills. Used cruise, set on 76 MPH for most of the ways. Fastest, about 85, slowest cruising about 70 for short bits. Topped off at the same gas station. Got a little better than 45 MPG for a little over half a tank (~360 miles). I've been getting 34-35 in mixed driving. A LOT of cold-engine driving, winter fuel, and cold-temperature commuting. When I got home I went to change the air filter, and it looks like it was sprayed with flat black Krylon on both sides. Scary that the 'clean side' was so dirty. Popped in a new filter, and I'm hoping that raises my FE quite a bit.
 

Losha

Veteran Member
Joined
Mar 8, 2005
Location
Sioux Falls, SD
TDI
06 Jetta TDI DSG, 2001 Golf TDI, Audi S6, A8, Toureg
Off topic but you have a 6MT or taller 5th in that Wagon ? What about even faster ? Wondering what she will do and how well planted it feels. I know my R32 feels rock steady at 155+ compared to other cars I've driven.
With his mods and if its stock 5sp his top speed would be limited to around 130mph on speedometer (actual speed 127mph will be), his RPM's would around 5500RPM (can't remember for sure).

I toped my TDI off at 125mph about little over year ago, don't remember where RPM's were but roughly around 5200rpm, possible might have gone little faster but road started turn had slow down.:eek: To 120mph it was easy achievable but rest of 5mph tool little longer, btw this is actual speed not just on speedometer. I had 215/45/17 wheels and my speedometer is only within 1mph off, I had it checked. My mods at time were stock 5sp, RC3, VNT15, boost controler, straight 2.5" exhaust, 11mm IP w/10mm head, Bosh 520 nozzles, IQ set around 3.2-3.6mg, boost at 18lb. Amazingly but my at that speed my car feels very stable & feels pretty relaxed compare other vehicles I driven at highway speeds. Anyway sorry for high jaking thread.
 

rotarykid

Top Post Dawg
Joined
Apr 27, 2003
Location
Piedmont of N.C. & the plains of Colorado
TDI
1997 Passat TDI White,99.5 Blue Jetta TDI
I did a highway mileage test yesterday. Totally warmed up the car, drove on the highway for a while, filled up, and went about 360 miles without stopping. I know at one point I had a vicious headwind, and sometimes a strong crosswind, but it's hard to tell when you're on the freeway. Route (I-25 south of Denver) was fairly flat (for CO), and traffic wasn't a factor. I coasted in neutral on all the big downhills. Used cruise, set on 76 MPH for most of the ways. Fastest, about 85, slowest cruising about 70 for short bits. Topped off at the same gas station. Got a little better than 45 MPG for a little over half a tank (~360 miles). I've been getting 34-35 in mixed driving. A LOT of cold-engine driving, winter fuel, and cold-temperature commuting. When I got home I went to change the air filter, and it looks like it was sprayed with flat black Krylon on both sides. Scary that the 'clean side' was so dirty. Popped in a new filter, and I'm hoping that raises my FE quite a bit.
At one time I made the drive from S west Denver to CO Springs ( ~ Academy & Austin Bluffs ) at least once a week . In a 99.5 Jetta 5 spd man TDI I clocked 51-53 mpgUS pretty consistently on the tanks that included that drive . The speeds varied from a low of 68-70 to a high of ~90 mph . It had 205 75 15s all around and had the timing jacked up to ~ 7-10 * BTDC .

Around Denver & CO Springs I would clock high 50s mpgUS tank after tank in this car .

The above is similar to what I can achieve in a B4 Passat TDI @ similar speeds in similar conditions on that drive .
 

NewTdi

Top Post Dawg
Joined
Jan 15, 2004
Location
NorCal
TDI
2003 Bora, Reflex Silver
Did my highway mileage test on Monday and yesterday. I did not start recording mileage sooner since it was so foggy I missed the station where I wanted to fuel up

Segment 1: Valero Station ($3.39/gal) Santa Nelia, CA to Grapevine - Laval Road exit.
187 miles
4.215 gallons
44.36536 calculated MPG
GPS Speed 75mph - averaged 74mph
ODO Speed 78mpg
Tires: 36psi

Segment 2: Grapevine - Laval Road to Santa Nelia (same station and same price)
188 miles (longer off-ramps traveling in Northbound direction)
3.930 Gallons
47.83715 Calculated MPG
GPS Speed 70mph - Averaged 69 mph
ODO Speed 73mph
Tires: 36psi

Segment 3 - Santa Nelia, CA to Concord CA
95 miles
1.935 gallons
49.09561 Calculated MPG
GPS Speed 65mph
ODO Speed 68mph
Tires: 36psi

Car was set in cruise control for all 3 segments except for when entering/exeting the highway.

Interesting finding: While my GPS had read distance of 188 miles the actual ODO reading was 186.5 - a difference of 1.5miles

Calculated MPG was on ODO reading and not GPS

The car needs some help because the mileage is not at all where it used to be. :confused:

Highway 5 in the early morning was patrolled both by CHP and different Sheriff agencies - I do not recall ever seeing a Sheriff's officer on that highway. :eek:
 

Bob_Fout

Oil Wanker
Joined
Sep 5, 2004
Location
Indiana
TDI
2003 Jetta - Alaska Green (sold) / 2015 GTI 2.0T
Completely normal MPG. There's probably some induced error due to short distances traveled.
 

NewTdi

Top Post Dawg
Joined
Jan 15, 2004
Location
NorCal
TDI
2003 Bora, Reflex Silver
Completely normal MPG. There's probably some induced error due to short distances traveled.
What would be the induced error? Maybe that traveling north on HWY is actually uphill? I fill it to the rim at the same stations at the same pump!
I picked highway 5 because the road is failry similar in both directions.

Going to the GTG in Oregon on March 6th so I can calculate then what the mpg's are over a longer distance, but when going over the mountains one side is steeper than the other and that would be somewhat of an induced error.
 

Derrel H Green

Top Post Dawg
Joined
Jun 2, 2002
Location
Murrieta, California
TDI
An '05 MBZ E-320 CDI (W-211) replaced the '10 TDI JSW
Winterized Fuel

The car needs some help because the mileage is not at all where it used to be. :confused:
:)

It is winterized fuel that is most likely costing you when it comes to better F E.

Wait until you are able to buy regular non-winterized fuel and see what happens!

:D

D
 

Bob_Fout

Oil Wanker
Joined
Sep 5, 2004
Location
Indiana
TDI
2003 Jetta - Alaska Green (sold) / 2015 GTI 2.0T
What would be the induced error? Maybe that traveling north on HWY is actually uphill? I fill it to the rim at the same stations at the same pump!
I picked highway 5 because the road is failry similar in both directions.

Going to the GTG in Oregon on March 6th so I can calculate then what the mpg's are over a longer distance, but when going over the mountains one side is steeper than the other and that would be somewhat of an induced error.
OK, filling to the rim and venting makes it more accurate, so those numbers are accurate for this purpose.

Driving the whole 470 mile distance in one shot (it's only half a tank) would be ideal though.
 

NewTdi

Top Post Dawg
Joined
Jan 15, 2004
Location
NorCal
TDI
2003 Bora, Reflex Silver
OK, filling to the rim and venting makes it more accurate, so those numbers are accurate for this purpose.

Driving the whole 470 mile distance in one shot (it's only half a tank) would be ideal though.
I am driving to San Diego tomorrow (I know I should have stayed in SoCal instead of coming back-up) so I can do a better average, however SoCal traffic will be a big variable.


Why wait to see what happens if I can do some maintenance before regular ULSD is out again in the spring? ;)
 

Derrel H Green

Top Post Dawg
Joined
Jun 2, 2002
Location
Murrieta, California
TDI
An '05 MBZ E-320 CDI (W-211) replaced the '10 TDI JSW
Btw

Segment 1: Valero Station ($3.39/gal) Santa Nelia, CA to Grapevine - Laval Road exit.
187 miles
4.215 gallons
44.36536 calculated MPG
GPS Speed 75mph - averaged 74mph
ODO Speed 78mpg
Tires: 36psi

Car was set in cruise control for all 3 segments
except for when entering/exiting the highway.
:)

You do know that for miles and miles prior to reaching the steep
Five Mile Climb to Gorman, there is a 1/2 (.5) percent grade?

Most people do not know this, but I do from my Trailways days and the Eagles with their
Detriot 8V 71s. They did not have enough torque to pull that 1/2 of one percent grade in
fourth, so I had to drop back to third where, at a governed 2100 rpm, was only 51 MPH.
Meanwhile, he comes the older Cummins equipped straight six geared for a top speed of only
65 MPH, but much more torque than the Detroit, and the old Cummins would blow right by me!
The Cummins did not know nor care about that long stretch that is .5 percent.

This minor upgrade is reflected in your poorer F E going South and the much
better F E you got when turning North and your better F E traveling North.

The trouble here in California is that there are relatively few stretches
where we can check out our F E for long distances on the level. :(

:D

D
 
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NewTdi

Top Post Dawg
Joined
Jan 15, 2004
Location
NorCal
TDI
2003 Bora, Reflex Silver
:)

You do know that for miles and miles prior to reaching the steep
Five Mile Climb to Gorman, there is a 1/2 (.5) percent grade?

Most people do not know this, but I do from my Trailways days and the Eagles with their
Detriot 8V 71s. They did not have enough torque to pull that 1/2 of one percent grade in
fourth, so I had to drop back to third where, at a governed 2100 rpm, was only 51 MPH.
Meanwhile, he comes the older Cummins equipped straight six geared for a top speed of only
65 MPH, but much more torque than the Detroit, and the old Cummins would blow right by me!
The Cummins did not know nor care about that long stretch that is .5 percent.

This minor upgrade is reflected in your poorer F E going South and the much
better F E you got when turning North and your better F E traveling North.

The trouble here in California is that there are relatively few stretches
where we can check out our F E for long distances on the level. :(

:D

D
Derrel,
I did not even "go up" the grapevine. I calculated my mileage in the valley ONLY! I choose the valley because speed could be consistent and traffic flows better. FE going North and South was different because I traveled at different speeds.
 
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