//// Best RPM to drive at for MPG for ALH /////

Andyinchville1

Veteran Member
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Apr 7, 2016
Location
Virginia
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2003 Jetta TDI wagon, 5 sp, 226K miles
HI All,

I watched a You tube Video the other day that said for max mpg you should drive at or just slightly above peak torque (1900) engine RPM.

But then again, I have read many posts that said you should drive in the highest gear at the lowest RPM without lugging the engine... ( I have been in 5th gear as low as about 1300 RPM on the flat without lugging).

On the other hand, some say to drive where the engine has its best BSFC (if BSFC what is this RPM on a TDI (2003 and).

Which of the above is the best to drive at or is there another better option ?

Also, does tuning change the equation any (I have a Malone stage 1).

I don't pulse and glide , shut off engine etc .... that's a little too hard core for me ... Just trying to drive steady and shift scientifically.

Thanks

Andrew
 

ranger pete

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Jul 29, 2011
Location
connecticut
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2011 JSW 6MT
The highest gear without lugging sounds best to me.

While an engine may be most efficient at the torque peak, you are pushing a lot of air out of the way at that speed.

If you can put along in the same situation in the same gear, at 1300 rpm, you may be running at a lower efficiency, but you are also doing a hell of a lot less work.


Sent from my iPhone using Tapatalk
 

scooperhsd

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Aug 19, 2003
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Kansas City KS
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NB, 2000, RED(5 Speed conversion) 2015 Golf SE
I prefer to go at the RPM where the turbo is starting to have some significant effect, so I get the excess air benefit. On my 2000 new Beetle this is in 5th gear (stock gearing) around 55-60 MPH / 1900 - 2000 RPM . I usually end up staying with traffic flow at 65-70 MPH :)
 

oilhammer

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Dec 11, 2001
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outside St Louis (where it's safe)
TDI
There are just too many to list....
I drive as fast as I reasonably can, and am perfectly content with 45-50 MPG, and laugh at people trying to hypermile and spend much more time getting anywhere doing it. I like knowing that no matter what, I am still using far less fuel than just about anything else I could possibly buy, let alone stand to drive.
 

sootchucker

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Colorado
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2015 Golf
I drive as fast as I reasonably can, and am perfectly content with 45-50 MPG, and laugh at people trying to hypermile and spend much more time getting anywhere doing it. I like knowing that no matter what, I am still using far less fuel than just about anything else I could possibly buy, let alone stand to drive.

this.
 

IndigoBlueWagon

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Aug 16, 2004
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South of Boston
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'97 Passat, '99.5 Golf, '02 Jetta Wagon, '15 GSW
I drive as fast as I reasonably can, and am perfectly content with 45-50 MPG, and laugh at people trying to hypermile and spend much more time getting anywhere doing it. I like knowing that no matter what, I am still using far less fuel than just about anything else I could possibly buy, let alone stand to drive.
Absolutely this. I would far rather save time than money on a road trip. Driving home from Washington DC week before last I could have kept the cruise set at my usual 75 or run with traffic on the NJ turnpike at 85-90. I picked the higher speed. Got home a half hour earlier than I would have otherwise. Worth it to me. And it was probably safer than driving slowly.
 

Mongler98

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Northern MD (HAGERBUSH)
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98 Jetta TDI AHU 1.9L (944 TDI swap in progress)
wind speed resistance, incline, tune, power mods, and other variables will change the answer to this question.
technically the direct answer here is 1st gear at idle. about 150 to 180 mpg maybe more. but that's not realistic.

for instance, i run a scan gauge II so i know what real time MPG and more importantly GPH are. the reality of driving is not what RPM is best, its about using the energy you spent in acceleration to its fullest potential, aka leaving room and braking less. learn to hyper mile your driving habits and you wont give 2 S's about what RPM your in.
 

Suzuki_dude

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Location
Manitoba, Canada
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'95 Sidekick
The correct answer for steady speed is whatever rpm puts you at the lowest bsfc point. Highest gear possible is a good rule to achieve that but there are exceptions.

http://forums.tdiclub.com/showpost.php?p=2076501&postcount=14

In my Sidekick I will cruise in town (50kph) in 4th gear which results in about 1300-1350rpm. 5th vibrates too much. Let's say it takes 10hp at that speed. Any lower gear is killing your mileage. I believe this is part of why I could consistently get 37-38mpg in town with 245/75r16 all terrain tires. I would accelerate fairly quickly and shift around 2500 in 1st and 2nd and then go straight to 4th. If there was someone slow in front of me I would shift sooner to keep the load up. Ideally you'd always be cruising lower than peak torque since bsfc starts to rise as you rev past peak torque. Usually people will go a little higher than needed to avoid downshifting for hills/passing. I don't mind shifting. That's why I drive a manual in the first place.
 

Andyinchville1

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Joined
Apr 7, 2016
Location
Virginia
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2003 Jetta TDI wagon, 5 sp, 226K miles

HI,

Great link ... I'll have to re read it when my brain is a little more alert ...lots to digest there but I like that they hit on all the points I was thinking about... chart was a little hard to read tho

As far as my simple methodology to see it what helps or hurts mpg wise , I typically try to drive 60 to 62 pretty much any time I am on the highway... (with at least 2 lanes in the same direction) .... if only a 2 lane road (1 lane each direction) , I typically do 50 - 55 but generally more towards the 50 side sometimes lower if I know its deer infested

It's not as bad as it sounds because typically I drive late night or wee hours in the AM when its nothing buy me , the deer and a few bad guys and cops out. I tend not to go fast mainly because of all the deer I've already hit even going relatively slow).

Anyways, my recently installed larger tires tends to put me closer to the peak torque at speed and my fuel mileage has gone up since the tires were put on (per scan guage I am about 1950 RPM at 59 MPH (per GPS)

Thanks for all the other replies too ( I drive expedited delivery so sometimes I still have to speed to make delivery times work out .... sheesh you think the surgeons could wait just a bit so I don't have to ruin my tank MPG efforts ! HA JK
 

ToxicDoc

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Mar 1, 2018
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Virginia, US
TDI
2001 Jetta, S7, .216
Did you reprogram your speedometer with those larger tires? Otherwise you'll have a false increase in your mpg
 

Andyinchville1

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Apr 7, 2016
Location
Virginia
TDI
2003 Jetta TDI wagon, 5 sp, 226K miles
Did you reprogram your speedometer with those larger tires? Otherwise you'll have a false increase in your mpg
Hi

I am having a guru work on my car soon and I'll ask him if he knows his to do that.

I mainly use waze and it has a speedometer on the screen ...

I Try to mentally remind myself to add 5 mph if using the cars speedo... ( I cant remember the difference is speed from the gps vs car speedo so I just chose 5 mph because it's a easy to remember.

Thanks
 

UhOh

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Dec 24, 2014
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PNW
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2000 & 2003 Golf GLS
Averaging 51.2 mpg over 87k miles. I use full travel on the GO pedal!

If I'm trying to clean up my average I go by my ScanGauge. I'll do various FE things if time and conditions permit (not in any hurry). But, again, I don't hesitate to nail it. I could probably get 53mpg (over the long-haul, not just a tank- I've done over 57mpg on a tank), but that's a 3% improvement which would come only by driving like I'm about to expire! (at some point driving like that is a safety hazard- not worth it)
 

Rrusse11

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Jan 23, 2014
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PA Deutsch Country
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2002 Golf, 5spd; 05 Jeep CRD
Driving like OH with my mods I'm lucky to get 40mpg around town. With diesel in one of the more expensive states at
$2.50/gal, so what? Nothing else on the road comes close for performance for the buck.
 

Curious Chris

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Joined
Jun 11, 2001
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Pineview GA
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Jetta Wagon 2003 RIP Rockford IL
There is a high torque value around 1950 RPM so that is where I drive as the engine is happy with the nice torque number. Yes I have the dyno data on my car.
 

Andyinchville1

Veteran Member
Joined
Apr 7, 2016
Location
Virginia
TDI
2003 Jetta TDI wagon, 5 sp, 226K miles
Averaging 51.2 mpg over 87k miles. I use full travel on the GO pedal!

If I'm trying to clean up my average I go by my ScanGauge. I'll do various FE things if time and conditions permit (not in any hurry). But, again, I don't hesitate to nail it. I could probably get 53mpg (over the long-haul, not just a tank- I've done over 57mpg on a tank), but that's a 3% improvement which would come only by driving like I'm about to expire! (at some point driving like that is a safety hazard- not worth it)
Hi,

Wow that is crazy good MPG ! , what mods do you have to your car ? I'm guessing very little idling and city driving ? Mostly flat land? do you hypermile ?

The most I ever got (so far with my new larger tires driving at peak torque in 5th gear, All highway , no real slow spots was 53 mpg (2 tanks in a row worth ... manually calculated .... so hopefully accurate .... lately I have been around 50 MPG ... not super good but liveable .. I hate getting under 50 MPG but I have had to drive 70 mph on several runs to make time / be on time for deliveries and MPGs fell to 48 ish

Sorry about so many questions BUT i must learn from the master ! ;-)
 
Last edited:

mech644

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Feb 7, 2007
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Blue Hill, Maine
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'00 Golf, '14 Touareg
Keep in mind that one of the best ways to keep these cars at peak efficiency is frequently drive them hard: accelerate harder than usual (preferably going uphill), hold the shifts longer for higher rpms, and generally excercise the turbo‘s vnt mechanism. Low sulfur diesel has helped with preventing the clogging of intakes, etc. But a regular flogging will go a long to way to keeping things inside clean and operating as designed.
 

LibertyHog1

Member
Joined
Aug 13, 2020
Location
Central, IL
TDI
2014 Jetta TDI, 6MT
I'm still figuring out best practices for fuel consumption on the diesel (all gasers prior to getting a 14 Jetta in July).

Best so far was 62.xx MPG after 904 miles on 14.49 gallons. Usually tank average is probably low 50mpg
(For comparison I had a 12 Sonic 1.4T manual that I had a best of 56.xx MPG over 500 miles on 10.xx gallons. And I had to really work hard for that, one interstate trip at 65mph would have dropped that average 2-3 mpg..... whereas I had 5 round trips on interstate with the Jetta on the 62mpg tank, and once with to-go construction traffic for 10-15 mins.)

Most things fuel related have crossed over directly (and mirroring the fuel mileage boosting thread) such as
- limited idling (of note the TDI has been much more forgiving than the gassers.)

- Keeping cruise speed down.... and in top gear (I've done a bit of cursory testing on the Jetta and at a given speed, dropping down a gear seems to reliably drop instant fuel economy 2-3 mpg per gear drop on a warm engine in steady-state conditions.)

- Long trips
- lots of coasting or downshifting instead of braking for turns and stops


The most noticeable difference I've found from my gas Turbo Sonic is the diesel has been way more forgiving to how you get up to speed; all other things being equal.
On a gas car there was a noticeable fuel economy improvement if one used minimal throttle and short shifted to get up to speed versus flogging it to get up to the same speed (eg lots of throttle and higher revs).

This diesel Jetta on the other hand doesn't seem to care. Granny it up to speed or rip it up to speed and the fuel economy average seems to end up at about the same place.
 

Andyinchville1

Veteran Member
Joined
Apr 7, 2016
Location
Virginia
TDI
2003 Jetta TDI wagon, 5 sp, 226K miles
Did you reprogram your speedometer with those larger tires? Otherwise you'll have a false increase in your mpg
No not reprogrammed yet but I have read that you can only correct speedo or odometer not both .... I may ask my guru when he works on the car next since he has the vag com software and computer etc...
 

Andyinchville1

Veteran Member
Joined
Apr 7, 2016
Location
Virginia
TDI
2003 Jetta TDI wagon, 5 sp, 226K miles
Keep in mind that one of the best ways to keep these cars at peak efficiency is frequently drive them hard: accelerate harder than usual (preferably going uphill), hold the shifts longer for higher rpms, and generally excercise the turbo‘s vnt mechanism. Low sulfur diesel has helped with preventing the clogging of intakes, etc. But a regular flogging will go a long to way to keeping things inside clean and operating as designed.
HI ,

I have been flogging the car sometimes to keep the turbo exercised etc ... so as not to have sticking

How does low sulfur keep the intake from clogging ? I thought the clogging was a result of oil vapors and diesel soot ?

Maybe a malone tune with dynamic EGR is as good or better than a full EGR block since it allows for fast warm ups then blocks off EGR when warm ?

I had though of EGR block but I like the idea of fast warn ups .... maybe leave the EGR cooler on (to cool the exhaust and warm the engine coolant faster) but block the autual exhaust gas from clogging the intake?
 

Andyinchville1

Veteran Member
Joined
Apr 7, 2016
Location
Virginia
TDI
2003 Jetta TDI wagon, 5 sp, 226K miles
wind speed resistance, incline, tune, power mods, and other variables will change the answer to this question.
technically the direct answer here is 1st gear at idle. about 150 to 180 mpg maybe more. but that's not realistic.

for instance, i run a scan gauge II so i know what real time MPG and more importantly GPH are. the reality of driving is not what RPM is best, its about using the energy you spent in acceleration to its fullest potential, aka leaving room and braking less. learn to hyper mile your driving habits and you wont give 2 S's about what RPM your in.
HI,

I have a scan gauge also in my car but some of my numbers off the gauge don't make sense .... what are some values you programmed into the unit to make some of the gauge readings make sense ? (example my MPH is way off , MPGs same thing no where close to hang calc etc...).

I think the manual said numbers are screwy for diesels unless corrected

Thanks
 

Mongler98

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Mar 23, 2011
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Northern MD (HAGERBUSH)
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98 Jetta TDI AHU 1.9L (944 TDI swap in progress)
all i can say is that you have to use the manual and google to find the settings. i don't remember what they are, also my car i had it on was a 1z
 

ToxicDoc

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Joined
Mar 1, 2018
Location
Virginia, US
TDI
2001 Jetta, S7, .216
No not reprogrammed yet but I have read that you can only correct speedo or odometer not both .... I may ask my guru when he works on the car next since he has the vag com software and computer etc...
That is correct. From the factory, the indicated speed is off by a few mph, but the odometer is accurate. Mine is about 4 mph fast at 60 mpg. Odometer is correct. When you change tire size (the circumference) you correct by the percentage difference from old to new. This will give you the correct odometer reading and the speed will be off but proportional to the old error.
 

Mozambiquer

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Versailles Missouri
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1998 VW Jetta TDI. 1982 VW Rabbit pickup, 2001 VW Jetta TDI
I've always been on the keep it slow group until now recently... Yeah, people hate us sometime, but I enjoy it. I kinda miss the slow pace life, but being married with a kid makes it harder.
Anyway, my record was 56mpg in my old rabbit pickup 1.6NA with the 4 speed.
Currently I drive a 2005 Passat wagon, and it gets far better fuel economy when you set the cruise at 75-80 compared to 55mph local driving (30mpg local driving, 40+highway)
On an alh though, it likes 65 mph better, at least that's what my golf 5 speed liked. I got 50mpg on a trip with it, then on the way back it got 39 mpg. That was stage 4 tuned, and the car was loaded. It was also winter time.
 

Turbospool

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Daleville Va
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2001 White TDI Jetta, 280k, 2003 jetta 270k
I no longer get the mileage I used to since adding a VNT 17 turbo, and upping to RC stage 3. Best setup for me was
1. Sprint 520 nozzels balanced.
2. EGR delete
3. RC stage 2
All the other mods had negligible input.... although everything helps.
I remember doing 12 tanks back to back hand calculated averaging 67 mpg. (I don’t care if you believe it or not, I know)
The best mod was my right foot (used a scan guage), had a 25 mile commute on semi rolling terrain one way, then back home. No speeds exceeding 60 mph. No shutting off the car, just watching my foot and having fun.
Would I drive this way ongoing? Nope! Had my experiment long enough. Now I drive for a different kind of fun..... Power it, and believe it or not I’m 65 :)
 

kjclow

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2010 JSW TDI silver and black. 2017 Ram Ecodiesel dark red with brown and beige interior.
Best milage I ever got out of my alh (2000 Beetle) was 56. Fresh oil change and running from Charlotte to the outer banks. All state highways with most speed limits at 55 mph. Kept cruise set around 60 and tach was just under 2000 rpm. Limited AC as it was mid spring and slightly overcast. Full run out and back in a day of 500+ miles.

I find that my 2010 jsw gets the best mileage (accroding to the dash) around 72 mph.
 

ToxicDoc

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Virginia, US
TDI
2001 Jetta, S7, .216
Best milage I ever got out of my alh (2000 Beetle) was 56. Fresh oil change and running from Charlotte to the outer banks. All state highways with most speed limits at 55 mph. Kept cruise set around 60 and tach was just under 2000 rpm. Limited AC as it was mid spring and slightly overcast. Full run out and back in a day of 500+ miles.

I find that my 2010 jsw gets the best mileage (accroding to the dash) around 72 mph.
You were going to a lower elevation too, so gravity plus a little extra oxygen and boost to help you. I can't get true engine mileage because I'm always going up and down steep elevations
 

kjclow

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2010 JSW TDI silver and black. 2017 Ram Ecodiesel dark red with brown and beige interior.
Running to the coast is about 600 feet of elevation change but I also came back. The change is so gradual from Charlotte to the coast, that you don't really notice it. In most spots, you would probably not even get much coasting on a bike.
 

TDIMeister

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Canada
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TDI
You can use up and downhills to your FE advantage. As long as the beginning and end of a given trip is about the same elevation, hills could give you better average FE than driving on perfectly flat road. The reason is that when you drive uphill (as long as you remain on the highest gear ratio without lugging the engine) you operate the engine at higher load, which from the BSFC graphs posted earlier in the thread is more efficient. Then, as long you're not using the brakes when the car is going downhill, the engine burns zero fuel to coast and gets maximum distance without getting back on the go-pedal. Always simply imagine using the brakes and the heat generated as wasted energy that came from the fuel to propel the vehicle. Of course, don't drive in any unsafe manner only to save a bit of fuel!

In a completely different car I have, a domestic automatic gasser (I know, but it's the wife's), I have been known to accelerate slightly at the foot of an uphill climb - below the threshold of the transmission kicking down - and progressively slow down to normal speed or slightly under at the top of the hill, all while trying to prevent leaving from the top overdrive gear. Otherwise, dropping to a lower gear when going uphill kills my FE far more than to accelerate before coming to the hill and remaining in top gear at all times where possible.
 
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