Barraged

I have had my 2015 Q5 TDI for about 6 months now (5,300 miles) and loving it. The difference in performance between D and S is pretty evident and I find myself driving mostly in S. In city driving, D keeps the rpm's very low, <2,000, and it feels like the engine is lugging, which I know is not good for an engine. I would like to get the best MPG and want to ask if it is more efficient to keep the rpm's in the 2,000-3,000 range (S), rather than 1,500-2,000 (D) for a given speed. What impact on mpg will this have? Watching the mpg gauge, it seems like there is very little difference, but S seems to place less stress on the engine.. Tnx for the feedback…

Dalancroft

Mine is a 2.0T but torque curves in both diesel and regular gas turbos tend to come on very quickly -- mine is 1,500-4,000 RPM if memory serves. Lower RPMs = less stress not the engine, not more. I only use S mode when, say, merging onto a freeway or climbing a steep grade. YMMV.

stash64

Not true. You can indeed "lug" an engine and create higher stress on the drive components at lower engine rpm. Just think about the amount of force you have to exert when riding a bike and trying hard to accelerate when you have shifted into too low a gear (ratio). If using "D", it's best to accelerate gently to avoid lugging.

However, I doubt the OP has to worry with the TDI. Diesel engines are very robust and designed for high torque loads. Our little turbo engines are a different story.

ex-quattro PETE

A modern auto trans will not lug an engine when left in D mode, no matter how hard you try. If you try to accelerate briskly, it'll just downshift.

ex-quattro PETE

For best MPG, leave it in "D".

Barraged

Thanx all for the feedback...

lja36

I do 3 things to improve low rpm running:

1) improve fuel quality. by improving fuel cetane, the engine runs more smoothly... this is particularly noticeable at very low rpms. by improving the speed of the fuel burn, power is delivered more smoothly, the turbo is also allowed to spool up more quickly... ironic that for both diesel and gas, better fuel equates to less turbo lag. the fact that you have to drive in "S" in order to be mechanically sympathetic leads me to believe that your car is unhappy with the fuel. I run mine with cetane boost and it is happy and responsive in "D" and can run under 2000 rpms all day.

2) after doing (1) I get into audi drive select and change the throttle response to dynamic (but not the transmission) that way I don't have to step very far for good pedal response.. if your car doesn't have the audi drive select option, you can borrow a VAG-COM and enable it anyway. note that doing this is far less effective unless you have done (1)

3) I specifically wanted the paddle shift option to participate more in the driving. if you leave it in "D", the car is reactive to a situation.. it downshifts in response to a demand for acceleration... you can always help the car if you can see ahead and anticipate the situation by manually downshifting first... it is a lot smoother to downshift under light load than to downshift under heavy load... a lot more mechanically sympathetic too. if you don't have paddle shift you can use the manual mode, but that is a lot less convenient than using the paddle shifts... I know people who have converted their steering wheels from non paddle shift to paddle shift, so you are not out of luck even if your car doesn't have it...

idale

You won't lug the engine unless you're at near-idle revs, and the transmission wouldn't really let you do that anyway (you wouldn't be getting actual throttle until it's downshifted). Running the revs lower will result in lower fuel consumption. From my personal experience, driving in S vs. D was more responsive (D's programming is much more relaxed, S assumes you know what you're doing and gives you whatever throttle you request right away) but at a cost of 2-3mpg (~22 vs. ~25 for my driving).

I normally run in D with manual override to anticipate things like turning since the transmission can't see and D's automatic selection won't give you power to get through the turn as quickly. I'll sometimes throw it into S to pull out into traffic really quickly, as well as occasionally to help give the turbo and exhaust more of a workout vs. simply cruising in D.

ParadigmDawg

I took my 2013 Q(gas) out of "S" two or three times.

I have yet to take my 2015 Q(TDI) out of it.

lawnmore

Just to be sure I understand, you are stating that drive select can be activated on a 2015 Q5 P+ TDI with a VAG-COM. If so do you know where I can find the coding for this? Thanks