135i Steptronic vs DCT

[mlai]

Just got a 135i convert (early 2010) Steptronic from my dealer here at a fairly good discount. I realize that the 135i conv from April onwards have DCT instead of steptronic. So for those fortunate enough to have driven both, can you please share your thoughts on the perceived differences?

I have never owned a DCT before.

1) Are there any difference in terms of acceleration off the start? On autos, I can lift off the brake and step on gas, the response is quite instaneous. On a test drove of an Audi with DCT (i know, i know, different car). When i lift off brake and step on gas, engine will rev but for a short period, seems no power to the wheels. Is this a characteristic of DCT vs Step (auto)

2) In terms of everyday city driving and not pushing the car hard, will I notice any major difference between DCT and Step?

Any other thoughts?

Thanks for putting up with a newbie

[MarkR171]

1. DCT has launch control which will allow you to rev the motor before launching, similar to pushing in the clutch and gas at the same time to rev the motor. Shifts are a lot faster (yes, people say .2 seconds, but if you drive both, you'll really understand how much faster DCT really is.) Upshifts in the most aggressive shift setting on the DCT will be executed without any throttle lift at all.

2. Every day driving in automatic (D) mode, no difference... though my every day driving is done in M (Manual) mode + sport button. So for me, there is a huge difference.


The major difference between Step and DCT is the manual mode. DCT is much quicker in terms of it's reaction to the driver's input. Steptronic and other conventional automatic transmissions always have a delay between driver input and the actual gear change. The DCT is instantaneous.

Another difference is rev-matched downshifts. The steptronic will not rev match on any downshift, while the DCT will rev-match perfectly on both automatic and manual mode downshifts.

[mlai]

Originally Posted by MarkR171

1. DCT has launch control which will allow you to rev the motor before launching, similar to pushing in the clutch and gas at the same time to rev the motor. Shifts are a lot faster (yes, people say .2 seconds, but if you drive both, you'll really understand how much faster DCT really is.) Upshifts in the most aggressive shift setting on the DCT will be executed without any throttle lift at all.

2. Every day driving in automatic (D) mode, no difference... though my every day driving is done in M (Manual) mode + sport button. So for me, there is a huge difference.


The major difference between Step and DCT is the manual mode. DCT is much quicker in terms of it's reaction to the driver's input. Steptronic and other conventional automatic transmissions always have a delay between driver input and the actual gear change. The DCT is instantaneous.

Another difference is rev-matched downshifts. The steptronic will not rev match on any downshift, while the DCT will rev-match perfectly on both automatic and manual mode downshifts.

Thanks for the detailed difference I bought the 135i for my wife which does not understand cars as well. So step for her is probably the right choice

[italia4]

Originally Posted by MarkR171

Another difference is rev-matched downshifts. The steptronic will not rev match on any downshift,

hmmm, my 335i with steptronic rev-matched when manually downshifting, it's very surprising the 135 step can not. are you sure about that?

[Emerson]

Originally Posted by MarkR171

Another difference is rev-matched downshifts. The steptronic will not rev match on any downshift, while the DCT will rev-match perfectly on both automatic and manual mode downshifts.

I beg to differ. My steptronic rev-matches when I downshift, atleast I think its does. It'll blip the throttle and you hear a nice vroom out of it, that's rev matching right?

[MarkR171]

Originally Posted by Nox

I beg to differ. My steptronic rev-matches when I downshift, atleast I think its does. It'll blip the throttle and you hear a nice vroom out of it, that's rev matching right?

I stand corrected, I remember someone saying the 335/135 steptronic rev matches, but the GM unit in the 128/328 does not.

[mlai]

My steptronic on the new F10 (ZF8 speed) also rev match when downshift as well. I kinda miss NOT rev matching so I can do engine braking going down hill........

[Lee123]

I bought a 135 with DCT in September. When the transmission developed problems earlier this month the dealer gave me a 328 with steptronic. Prior to buying the 135 I owned a 2010 370z automatic.

The one negative I noticed about the DCT is that it definitely has a slight lag when you take your foot off the brake and step on the gas. To be honest, the 328 with steptronic gets a quicker jump off the line than the DCT. So did my 370z. I missed that with the DCT. Yes, the DCT has launch control. I never got to use it because I only had 500 miles on my car when it went into the shop, but it doesn't seem like something you would use in day to day driving pulling away from lights. It only makes sense that the DCT would take a tiny bit of time to get going, it is like a manual transmission that doesn't know it is time to start letting the clutch out until you start pressing the accelerator. It takes a fraction of a second to react. A regular automatic has pressure built up and is trying to creep forward even before you touch the gas. It is instantly ready to go.

Now for the positives. The DCT shifts much faster than any automatic I've ever seen. It responds to driver input much more quickly than a normal automatic. In the 3 weeks that I drove my car I was constantly impressed with the transmission. I can only imagine what it would be like once the car was broken in.

In answer to part two, just driving around in D mode there's not much difference except one little thing that I really liked. The DCT shows you what gear it is in all the time on the display between the speedometer and the tach as D1 through D7. I liked that a lot.

[mlai]

Originally Posted by Lee123

I bought a 135 with DCT in September. When the transmission developed problems earlier this month the dealer gave me a 328 with steptronic. Prior to buying the 135 I owned a 2010 370z automatic.

The one negative I noticed about the DCT is that it definitely has a slight lag when you take your foot off the brake and step on the gas. To be honest, the 328 with steptronic gets a quicker jump off the line than the DCT. So did my 370z. I missed that with the DCT. Yes, the DCT has launch control. I never got to use it because I only had 500 miles on my car when it went into the shop, but it doesn't seem like something you would use in day to day driving pulling away from lights. It only makes sense that the DCT would take a tiny bit of time to get going, it is like a manual transmission that doesn't know it is time to start letting the clutch out until you start pressing the accelerator. It takes a fraction of a second to react. A regular automatic has pressure built up and is trying to creep forward even before you touch the gas. It is instantly ready to go.

Now for all the positives. The DCT shifts much faster than any automatic I've ever seen. It responds to driver input much more quickly than a normal automatic. In the 3 weeks that I drove my car I was constantly impressed with the transmission. I can only imagine what it would be like once the car was broken in.

In answer to part two, just driving around in D mode there's not much difference except one little thing that I really liked. The DCT shows you what gear it is in all the time on the display between the speedometer and the tach as D1 through D7. I liked that a lot.

I see. The Audi A5 cab was the first DCT car that I test drove and I felt so stupid complaining to the salesperson that the car is slow off from start now

[RPM90]

Originally Posted by MarkR171

I stand corrected, I remember someone saying the 335/135 steptronic rev matches, but the GM unit in the 128/328 does not.

The 135i step does rev match, and it's actually quite fast to respond when you manually select gears. It's quite amazing how fast it does respond for a torque converter automatic. Very very few TC automatics are as quick as the ZF unit.

From my last 328i loaner, I believe th GM Step also rev matches in auto and manual modes, unless I remember this incorrectly. The big difference to the ZF unit is that the GM trans doesn't respond as quickly to manual gear selection. Though it too is pretty impressive compared to some "manu-matics".

[MarkR171]

About the dct being slow on brake to gas changes, try driving with the sport button on. It makes the throttle more sensitive. I don't notice this as I drive in manual + sport.

[Mikeshot1]

So my 2008 steptronic has rev matching like the 370Z manuals have with the option of course?

[spyderx]

Step does have gear indicator on 135i, as I recalled.
I was impressed how responsive this auto was! Quickest shifts I've experienced, using the gear shifter. There was slight delay using the paddle shifters.

I test drove DCT couple times on N55 and on the second occasion I did feel noticeable lag in gear changes! Then the CA pushed the sport button, I think, then this lag disappeared. I'm not sure if I could live w/ that lag... or having to push that button.

Maybe I'll stick to 6MT ordered and save $1500 and 65 lbs.

[daixloxbmw]

comparing my old 2008 335i coupe with Steptronic and my new 2011 135 coupe with DCT, one major difference i have noticed (aside from the aforementioned quicker/sportier shifts) is the slight delay while switching from R to D to R while parallel parking. during these transitions, the transmission definitely feels like a traditional manual in that the clutch is slightly slipping and slowly engages to give you smoother power delivery. the engine revs quite a bit more than it would normally in a regular torque converter auto.

aside from that, the DCT is really superior in every way, performance-wise, fuel economy-wise and even in smoothness once it gets moving. it seems like it still retains some of the traditional manual characteristics when going R to D to R and the quick launch from complete stop.

lastly, the main beef i have with DCT is that the M/S slot is locked out until you engage D first. this is a personal beef because i drive exclusively in manual mode and with Steptronic, I could start in P and shift directly into M1 with a 'J' motion in one smooth step. however, with DCT, the M/S slot to the left of the starting position is locked out until you first engage D. so i have to pull back to D, wait a split second for the M/S slot to be unlocked, then pull to the left to engage M1, which is now a two step process.

i really hope shiv can tune the Procede to unlock the M/S slot from the beginning. i see no reason why the M/S slot is locked anyway. as long as I am pressing down on the brake and holding the shiftlock button, whats the difference between shifting into M/S versus D? sorry for the rant...

[Jeef Beef]

The slight lag of the DCT that everyone refers to is not a fault of the transmission, but simply the nature of its setup. The DCT is much like a traditional manual in that it has a clutch (albeit two of them) that needs to be slipped in to move the car from a standstill. That would be the 'lag' being referred to, but it shouldn't feel any different than driving a normal manual.

The steptronic is a traditional torque converter automatic - the fluid coupling means that the engine is always engaged to the wheels so that the acceleration feels more 'instantaneous'.

On another note, I'm quite certain that all automatics in the BMW family perform throttle blips on downshifts. The ZF unit in the 135i is one of the best in this regard.

[daixloxbmw]

Originally Posted by Jeef Beef

The slight lag of the DCT that everyone refers to is not a fault of the transmission, but simply the nature of its setup.

this seems to be a contradiction. the setup = the transmission. so therefore it is a fault of the transmission.

i'm not dogging on the DCT transmission, i love it, in fact! however, the OP asked for differences between Steptronic and DCT and this is a valid one and it is a fault of the transmission since it does not occur in any Steptronic or any regular torque converter automatic.

EDIT

Originally Posted by Jeef Beef

That would be the 'lag' being referred to, but it shouldn't feel any different than driving a normal manual.

just to add, if you're saying that this lag is exactly like a traditional manual, then it just further proves that it is a valid difference to the Steptronic and also that it is a fault of the setup or transmission or whatever you want call it.

[DSB135i]

Night and Day difference! The DCT is faster put the shifts are so quick. You can go from 7th to 5 so quick! Honestly if I do get another automatic it will have to be the DCT!