Efficient Use of the 3.0 TDI in a Q5 -- Thoughts?

Mythdoc · February 16th, 2017, 14:31

I posted this in the AudiWorld Q5 forum and got basically no response. There are a few diesel owners over there but most are gasser owners and not TDI enthusiasts who want to know all about the engine or care that much about fuel efficiency.
I come over from a 2011 Touareg TDI with vastly different driving characteristics to my new (for me) Q5. That bigger rig with the gen 1 engine would upshift anywhere from 2200 rpm in sedate driving to 3500 in spirited driving. Sport mode wasn't particularly useful for it.
My Q5 TDI wants to upshift no higher than 1800-1900 in normal driving mode, maybe 2500 if I really push down on the pedal. It doesn't seem like it even uses the meat of the torque and hp curve this engine is blessed with. Not only am I not getting the performance the engine is capable of, if I am running at low revs using turbo boost I don't see how I am saving any mpg. It almost seems like Audi engineered the comfort mode to shift like a gasser.
I have paddle shifters (nice feature) and started off using them to downshift in normal mode when I thought I was revving too low, but now I think driving the car in sport mode and using the paddle shifters to upshift would be more suitable, more enjoyable, and possibly even more fuel efficient.
What do you all notice about your vehicle?
For an explanation of why 2000-3000 is the most fuel efficient rpm for a TDI when accelerating, see this link:
http://forums.tdiclub.com/showthread.php?t=335035

Mythdoc · March 4th, 2017, 10:57

Update: just using the paddle shifters in full manual comes out best.

Fantastic feature. On highway, comfort setting.

winks · March 9th, 2017, 07:58

not sure about the 2000-3000 rpm theory...I can never get down below 10L/100km in demonic mode, but can manage 6.1L/100km in comfy mode where it shifts below 2K like you said.

Mythdoc · March 11th, 2017, 06:07

Well, that's what the science says, but I agree it's hard to prove it in real world experience. My mpg fluctuates on quality of fuel, temperature--so many factors. My 2011 Touareg never seems to have an issue knowing what gear to be in. The Q5--not complaining, this is a nice problem to have-- seems to have an extra gear for the power of the engine.

VeeDubTDI · March 11th, 2017, 06:42

Using more RPM is not going to be more fuel efficient. The most efficient way to drive is to shift as early as is practical with gentle acceleration. Higher engine speed means more friction and more pumping losses.

Mythdoc · March 11th, 2017, 14:42

Hmmm. I think Vekke has pretty much proved otherwise.

http://forums.tdiclub.com/showthread.php?t=335035

VeeDubTDI · March 11th, 2017, 15:18

Vekke accelerates at high engine load followed by coasting in neutral to preserve momentum. That's very different than just driving at higher RPM.

Try some different driving styles, monitor fuel consumption, and do whatever works best for you.

Mythdoc · March 11th, 2017, 20:05

Quote:

Originally Posted by VeeDubTDI

Vekke accelerates at high engine load followed by coasting in neutral to preserve momentum. That's very different than just driving at higher RPM.

Try some different driving styles, monitor fuel consumption, and do whatever works best for you.

Yes, and "just driving at higher rpm" is not what I wrote anywhere. The thread was entitled "efficient use of the TDI engine" and the specific idea under inquiry was shift points under acceleration. On the other hand, your statement that "efficiency is best shifting as soon as possible under gentle acceleration" does not seem to be borne out by people who have tested TDI efficiency under real world conditions.

mech644 · March 12th, 2017, 18:24

Actually shifting early in the rpm range is one the key elements of how manufacturers are achieving EPA rated mpg. Shifting early raises the percent of load factor the engine is experiencing. For average driver low rpms at high percent of load = most efficient use of gas/diesel consumed.
I've seen this born out in '12 audi a3 DSG TDI, '06 Jetta DSG TDI, '14 Touareg TDI, and '15 Golf 1.8tsi auto. If left in normal drive all shift early, yes it feels like engine is lugging because it is. Do I like it? Hell no, shift'em all manually when I'm driving.
As transmissions have gained more gears it has allowed a cars management system to shift early and often.
If VW/Audi could have used a more efficient map of fuel/boost curves/shift points and not suffered on the sales side I'm sure they would have.

VeeDubTDI · March 18th, 2017, 07:23

Quote:

Originally Posted by Mythdoc

Yes, and "just driving at higher rpm" is not what I wrote anywhere. The thread was entitled "efficient use of the TDI engine" and the specific idea under inquiry was shift points under acceleration. On the other hand, your statement that "efficiency is best shifting as soon as possible under gentle acceleration" does not seem to be borne out by people who have tested TDI efficiency under real world conditions.

You're right - I retract my gentle acceleration statement.

However, you did state that your car upshifts early even under moderate to hard acceleration. That's good because it keeps the engine in its peak BSFC efficiency, which favors high load and lower RPM (but not too low).

Mythdoc · March 18th, 2017, 14:40

^^yes, it likes to shift early. The driving dynamics are taking some learning on my part, after the Touareg gen 1 TDI, But I am seeing mpg around 32-33 in mostly rural and highway driving, so all is satisfactory. Love the vehicle so far.

VeeDubTDI · March 19th, 2017, 03:23

Quote:

Originally Posted by Mythdoc

^^yes, it likes to shift early. The driving dynamics are taking some learning on my part, after the Touareg gen 1 TDI, But I am seeing mpg around 32-33 in mostly rural and highway driving, so all is satisfactory. Love the vehicle so far.

That's pretty impressive fuel economy for the size of the vehicle and engine. You really can't get that kind of efficiency in any other similarly priced SUV on the market.

psd1 · April 4th, 2017, 16:02

I've just put the second tank of fuel in our 14 Q5 TDI and am showing some good numbers, first tank was 33 MPG and this one looks to be similar if not better. We also had a 12 Treg Lux that we drove for a few months before the buyback was confirmed, it is now parked until it goes back to mother VW, but the difference overall in the vehicle is astounding. Fit, finish and quality much better in the Audi.

I would love to know where the tdiclub fo Q5's is, there has to be a place with info on improving MPG, etc.

mech644 · April 4th, 2017, 17:32

Q5, and 7, is here
http://forums.tdiclub.com/forumdisplay.php?f=84
Pretty limited activity, similar to Touareg in that lack of #s on the road = lack of people interested in the attendant forum.

Mythdoc · April 13th, 2017, 14:20

Had a nice 35.6 calculated tank today. Summer diesel coming in...and I do really enjoy the level of control with my paddle shifters!