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TDI Fuel Economy Discussions about increasing the fuel economy of your TDI engine. Non TDI related postings will be moved or removed.

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Old September 2nd, 2004, 07:38   #1
Blue_Thunder
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Join Date: May 2004
Location: Beetle Nation
Default Optimal RPM for maximum fuel efficiency

Could somebody tell me what the optimal RPM would be for my TDI-PD for maximum fuel economy? I've read 2,000 RPM and 2,500 RPM.

2,000 RPM on my TDI-PD, DSG Beetle puts me at precisely 60 miles per hour, in sixth gear.

2,500 puts me up around 65-70 mph.

So, does anyone have technical knowledge on what the most efficient RPM is for highway cruising?

Thanks.
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Old September 2nd, 2004, 07:53   #2
tditom
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Join Date: Sep 2001
Location: san antonio
Fuel Economy: Golf: 54/48/43.5 B4 Passat: 52/48.5/45 B5.5 Passat: 30 mpg mixed
Default Optimal RPM for maximum fuel efficiency

2000 rpm will net you better fuel economy than 2500 rpm. The max torque in the PD is supposedly available from 1800-2400 rpm. Wind resistance comes into play over 60 mph, so slower = better mileage.

hth
-tom
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Old September 2nd, 2004, 07:54   #3
Drivbiwire
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Join Date: Oct 1998
Location: Boise, Idaho
Default Optimal RPM for maximum fuel efficiency



The best range falls within the 1900-2200 rpm range give or take.

DB
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Old September 2nd, 2004, 08:00   #4
tditom
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Join Date: Sep 2001
Location: san antonio
Fuel Economy: Golf: 54/48/43.5 B4 Passat: 52/48.5/45 B5.5 Passat: 30 mpg mixed
Default Optimal RPM for maximum fuel efficiency

DBW- Do you have anything like that for the PD engine? The VW web site states 177 ft-lbs from 1800-2400 rpm.

-tom
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Old September 2nd, 2004, 10:06   #5
Blue_Thunder
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Default Optimal RPM for maximum fuel efficiency

Wow, once again tdiclub.com has proven itself to be a truly amazing source of information.
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Old September 2nd, 2004, 15:44   #6
maxforce
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Join Date: Aug 2003
Location: VA
Fuel Economy: Great on all
Default Optimal RPM for maximum fuel efficiency

I will give up a couple of miles per gallon to try and keep the intake clean and have a more "spirited" drive. I shift at 3k to 3500 and have averaged 49.2 for 25000 miles. As high as 55mpg.
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Old September 2nd, 2004, 19:25   #7
dbb635
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Location: Montreal, Canada
Default Optimal RPM for maximum fuel efficiency

I have a Tip with 19000km on it now, I usually get 750-800km per tank vented with about 58.5litres. If I'm not mistaken, that works out to about 30mpg us and 35 Imp MPG. I cant understand how I regularly see 50+ with these cars, I know I am in traffic for a minimu of 1hr per day, but 15 pg diff seems quite high. I'm not complaining, just confused...
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Old September 2nd, 2004, 20:14   #8
Ramsey
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Join Date: Jun 2004
Location: Madison WI
Fuel Economy: 48/44/37
Default Optimal RPM for maximum fuel efficiency

The tiptronic is still an automatic, and they all lose efficiency in the torque converter. I rarely hear of automatics doing better than 38. main reason I didn't get the passat wagon.
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Old September 3rd, 2004, 07:14   #9
fresheverytime
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Join Date: Dec 2002
Location: Burlington ON
TDI(s): 2004 TDI PD
Default Optimal RPM for maximum fuel efficiency

My best tank so far is 901kms with the Tiptronic... 54.6l to fill (vented) -> Low fuel light came on as I was pulling into the station.
33000kms on the dial and:
Lifetime average of 6.27 l/100kms (37.54 mpg)
Best tank of 5.13 l/100kms (45.86 mpg)
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Old September 3rd, 2004, 20:50   #10
TornadoRed
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Join Date: Aug 2003
Location: Saint Paul (ex-San Diego)
Fuel Economy: 52/41/36 (497k miles)
Default Optimal RPM for maximum fuel efficiency

Quote:
I know I am in traffic for a minimum of 1hr per day, but 15 pg diff seems quite high. I'm not complaining, just confused...
I spent 90 minutes driving home this evening, about 30-35 miles. Mostly in 1st and 2nd, occasionally 3rd gear. This tank will suck for fuel mileage.

If you want to see 45-50 mpg (US), then change your job and residence so you have a nice long 55 mph drive with no stoplights or traffic.
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Old September 3rd, 2004, 23:38   #11
Wee_Car
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Join Date: Jun 2004
Location: Maine
Fuel Economy: unknown
Default Optimal RPM for maximum fuel efficiency

I think you will find your best fuel economy at about 1500 rpm or at 45-50 mph. My wife regularly gets high 50's with her '03 manual on a 26 mile commute with only two traffic lights and a steady 45-50 mph speed. My moms '04 tiptronic can't get out of the mid 30's and I doubt it will gain much more, even after breakin. When I drive my wifes car, I shift at least 1000 rpm higher and drive at least 10 mph faster. My fuel economy is about 45 mph, so there is a big hit on how you drive these things. BTW my Ford powerstrokes get their best fuel efficiency at about 1400 rpm according to the computer.
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Old September 29th, 2004, 10:36   #12
Xgaz
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Join Date: Sep 2004
Location: West of Montreal, Quebec Canada
Default Optimal RPM for maximum fuel efficiency

I've noticed the same for my Tiptronic, so now I'm driving it as if it's a manual tranny.

Anyone know if that will make a difference in the milage?
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Old September 30th, 2004, 04:50   #13
TDIMAXIMA
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Location: MARKHAM, ONTARIO, CANADA
Default Optimal RPM for maximum fuel efficiency

For canadian drivers, I get between 900-950 km's a tank right around the fuel light comes on. I drive 98% on the highway of probably an average speed above what is posted. I think my mileage is ok, but not amazing, but my speed is the reason, Im regulary over 3000rpms.
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Old October 2nd, 2004, 10:39   #14
PolarBear
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Join Date: Sep 2004
Location: St-Lazare Qc
Fuel Economy: 5.2 L/100Km
Default Optimal RPM for maximum fuel efficiency

My present average is 5.3L/100km on an average of 50litres fillup. My best up to date is 5.1L/100 (968.8Km on 49.4 litres). My driving is mostly highway with an avg. speed of 120Km/Hr. I shift @ 2000rpm to 2100rpm and easy on the accelerator. Heck of a difference with my previous vehicle: 1/2 ton Chevy Pick-up with 125Litre tank Ouch!
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Old October 3rd, 2004, 12:41   #15
rickdick80
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Join Date: Mar 2004
Location: Detroit near-northern suburbs
Fuel Economy: 45.4 / 41.4 / 38.7
Default Optimal RPM for maximum fuel efficiency

DBW-

Does that graph only represent WOT curves? I wonder if the torque peak

[edit: it is my understanding that torque peak and BSFC peak tend to be nearly on top of one another]

occurs at the same engine speed at 10% throttle, 20% throttle, etc. Does anyone know if torque peaks tend to shift due to throttle input?
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