Driving in 'S'

[Bailes1992]

My Volvo V40 with it's 2.0 4 cylinder 150bhp diesel engine has a conventional torque converter Aisin TF71-SC gearbox.

It's my first real auto, in the UK we generally all drive manuals. That said, I've done many tens of thousands of miles in my Fathers '12 BMW 320d with a ZF 8HP45 when I was in my late teens/early twenties and still living at home.

If I drive an equivalent 4 pot passenger car diesel with a manual gearbox I generally find myself accelerating between 2,000rpm to 3,000rpm and settling the car to 'cruise' around 1,750rpm to 2,250rpm. For example, my last car (2016 Ford Focus 1.5TDCi) to accelerate to 30mph I would use 1st and 2nd gear, changing up at 3000rpm and once up to speed, select 3rd with the RPM around 2000rpm and maintain 30mph.

My reasoning for this was is that it doesn't lug the engine and possibly cause excessive wear to the dual mass flywheel, the drive was generally smoother with less NVH and if I needed to accelerate quickly then the engine was ready to go with next to no turbo lag, just put your foot down and off you go.

My Volvo in 'D' changes up around 1,750rpm to 2,000rpm and can cruise as low as 1,100rpm. This regularly causes a harsh vibration and deep drone through the car, especially if you are driving on the flat and then start to go up an incline as the box is very reluctant to down shift.

If I drive in 'S' then it works much like how I would drive a manual. It changes up between 2,500rpm and 3,000rpm for general driving and cruises around 2,000rpm. I find the gear changes faster, but still just as smooth, the car drones and vibrates less, the car is quicker to accelerate if I need it and I've noticed next to no difference in fuel economy.

In 'D' the gearbox has a clutch which disengages the engine form the torque converter to minimise load on the engine at idle and save a little fuel. In 'S' this feature is deactivated.

So my question...

Will driving in 'S' long term cause any extra wear on the gearbox over driving in 'D'?

 

[CharBaby]

Well, today's engine are actually designed to LUG which is allowed by the automatic transmission. Being in Drive(D) in some vehicles it actually the ECO Mode. So, lugging is not really a problem. This is for better fuel economy(keeping the RPMs as low as possible).

If you think the engines are droning(LUGGING) now, try a CVT tranny.

Using "S"/Sport Mode just keeps the RPMs higher(or I should say, ready to REV up faster) for better throttle response(which you're already aware of). Even when driving in "S" Mode, and by holding a steady throttle position e.g., while highway cruising, the tranny will relax until extra throttle tip-in or wide open throttle(WOT) is given/required. THEN my friend, the RPMs shoot high(er) for that better throttle response, in which some people call power.

Keeping the engine in "S" Mode can use more fuel as every throttle tip-in allows the RPM to shoot higher than in "D" Mode where the engine is in more of an ECO Mode, if we can call it ECO Mode???

But, to answer your question about hurting anything(other than fuel economy) by using "S" over "D", all I can say is...if it would seriously hurt anything, the engineers wouldn't give us the choice.

I don't know if I said this correctly but, it's how my brain works.

 

[BMWTurboDzl]

Yes but imo the question is how much additional wear-n-tear which is nearly impossible to quantify on a forum like this. Sure you can mitigate that accelerated wear by changing the ATF more often but that's just more about being hopeful. Besides if for example the life of the transmission in "D" is 150k miles and when in "S" it's 125k miles. Does that really matter?

 

[dbias]

I wouldn't think a transmission would give two hoots when it shifts, a shift is a shift, it's the engine operating at higher rpm is the difference. My A4 and jetta both have Sport mode and are more responsive to pedal inputs and hold each gear a little longer than in D. My work Van's have tow/haul mode that is kinda the same as they hold gears longer resulting in higher rpms but I have heard in this case it is easier on the transmission as they hunt less for the right gear when hauling heavier loads.

 

[supton]

I would think it would be programmed to avoid issues. But every maker is different. If I put my truck into S, it does squat for shift points. All it does is allow me to lock out gears above whatever number is shown on the display--S4 means it will shift 1-4. S5 means 1-5. Etc. [Supposedly if I turn on both S and tow mode, S over-rides tow mode shift points!]

If anything I'd think a true S mode would firm up shifting, leading to less slippage during gear changes, but that would again be dependent upon the maker (perhaps they cut power during shifting and thus it's a non-issue).

 

[JustN89]

I don't think extra wear occurs just because the transmission is in 'S' mode versus normal driving. However, and this is true in my car but I can't speak for others, when I'm in 'Sport' versus Eco/Normal, I notice the transmission is much more willing to downshift leading to more actual shifts over the course of my daily driving. A transmission that shifts more will have a shorter life span than similar transmissions shifting less, so it's possible that driving constantly in 'S' might cause the transmission to shift more often than normal and cause some accelerated wear. That said, if you stay on top of ATF changes then I'd say you'd probably have a longer living transmission than most people on the road.

 

[Pelican]

I don't think that it will wear faster. These days everything is electronically controlled so the disengagement/engagement occur in a fraction of a second. The engine/tranny of today's cars is slanted toward economy and not performance, so if you want to drive in S mode change the oil/filter twice as often and so for the transmission fluid and you are good to go.

 

[JLTD]

No worries. Drive on in S.

 

[Trav]

No additional wear, in fact there may be less because of no clutch operation at idle but fuel economy will be affected.

 

[Hall]

I think fuel economy requirements (or desire) drive a lot of this. I have a 2008 Infiniti G35 and it can get exciting if you really get on the throttle but in normal, daily driving, it does what I consider "short shifts", especially in 2nd gear (going into 3rd) and slightly better in going from 3rd to 4th. It's similar to what you're Volvo is doing, shifting around 2000 rpm. I don't worry about it personally....

Now, my wife has a Ford Fusion w/ 1.5L Ecoboost and I tend to drive it in "S" mode all of the time. It's even "lazier". Then again, in city driving, it gets 45% better gas mileage than the G35.

 

[Whimsey]

Originally Posted by hallstevenson

Now, my wife has a Ford Fusion w/ 1.5L Ecoboost and I tend to drive it in "S" mode all of the time. It's even "lazier". Then again, in city driving, it gets 45% better gas mileage than the G35.


We have a 2017 Explorer with the 2.3 EB which I believe has the same transmission as your Fusion, the 6F35. It up shifts at different speeds depending on how far you push the throttle while accelerating. I accelerate like a "grandpa" so it up shifts quickly. My wife drives like Danica Patrick on the race track so it doesn't up shift as soon. As for steady speeds in the 35 to 50 mph range of secondary roads in "D" it seems to be on the point of "lugging", but it doesn't. Shifting into "S" mode raises the rpm's enough to not feel like it's an the verge of lugging. On the highway I just leave it in "D" and it's fine. Today's computer controlled transmissions can adapt to various driving styles but their ultimate goal is to still provide the best mpg. At least in some cases they provided alternatives, such as sport mode and paddle shifting to liven things up

.

Whimsey

 

[KrisZ]

That's just the way diesels are, they have a lot of NVH at low RPM, but that doesn't mean the engine is being lugged or that it is harmful to the engine.

I've logged some carburated motorcycle engines in the past and their behaviour is really, and I mean really harsh when they experience true lugging.

The last modern engine that I was able to lug was my 95 Accord with the 2.2L four banger. Below 1500 RPM, even a gentle application of gas pedal would result in the engine shaking very badly. I had to keep that one at about 1800RPM and it made stop and go driving more challenging.

Everything else I drove since then I was not able to lug unless the RPM dropped to 1k RPM.

 

[Hall]

Yes, same transmission though I suspect there's some tuning differences between the vehicles. It does shift based on throttle input but I don't purposely drive gentle or hard, just "normal". It just feels closer to my G35 in around-town driving and shifting when it's in "S" mode. On the highway, I use regular Drive mode, of course. I love seeing it register ~34 mpg when cruising at 70-75 mph. It will do 38-39 mpg if you set the cruise control at a mind-numbing 55-60 mph, by the way !