JDN

You can flip by them so fast they never activate. Two quick flips from 6th puts you in 4th. I like sticks, too. They both have advantages, but the overall convenience of the SMG has got to be the biggest plus.

heezy545i

JDN,

What would you consider the advantages of a manual to be?

pennetta

edl, I have found everyone here in this forum to be very credible with their views, opinions and experiences. One thing that I try to remember myself when I pose a question is does the person answering actually have extensive first hand experience with the hardware and model car that I am questioning or are they assuming or repeating something they feel or heard. The SMG concept has been very misunderstood but virtually everyone that actually has one loves it.

Mercy

dito!

JDN

JDN,

What would you consider the advantages of a manual to be?
[/quote]
One advantage is shift speed. No way can the 545 SMG match a speed shift except when that pesky little bypass valve in the manual gets in the way sometimes. I've had that happen a few times with the 540. Neither does the manual have as much slippage on take off as does the SMG. While the SMG seems to have a quicker response, the slippage is there just like in an automatic. That slippage seems to cost about one mile per gallon on overall fuel economy.

The OBC seems to select the minimum SMG shift points whereas with a stick you can shift by the seat of the pants based on torque.

The problem with the manual is the over revving threat on the speed down shift. That is a biggie that is neatly handled with the OBC and SMG. So, bottom line is that I would probably do the SMG again and again and again. Just wish it would shift as fast as the one in the M3.

edl

Thanks to all for the great contributions.

Rudy, a special thanks (as EBM suggests) for the great .pdf you posted in the FAQ string re smg as published by bmw. As many have now noted, you can skip gears - the bmw documents states you can skip 1 gear (by way of example), i wonder, is there a limit to how much you can skip - i suspect that in order to protect on over high revs it won't let you down shift beyond a point where it would exceed redlining - as JDN points out this is one of the benefits of the smg - i.e., that you can't accidently downshift too far.

JDN, when you say the shifting is slower, this really surprises me (bear in mind i haven't ever driven an smg so part of the answer is to do an extended road test, which i will do), but i thought one of the advantages to smg was that it could shift faster than a human could...period. No? Also, when you mention slippage and it being like an automatic in this regard, can you describe a bit more about what that is like?

thanks,
edl

Hormazd

JDN

Re: slower shifting, depends on the skill level with a stick shift, I guess. For someone with limited experience with a stick, the SMG would be faster. For a skilled driver, the stick will be faster, but the ever present risk of overshifting is a risk to be considered. The 545 SMG definitely has seams in the shifting whereas the M3 SMG demos I have watched seem absolutely seamless.

Slippage is what happens when starting from a dead stop. The engine has to rev in an automatic to get the hydraulics churning enough to move the transmission. The classic slippage was experienced when starting off in the original Chrysler automatic transmissions in the Dodge and Chryslers of 1948 vintage, IIRC. They were called Fluid Drive and the there was a lot of revving, then creeping, and finally the engine and the transmission were mated at about 25-30 mph. General Motors and Ford had them beat from the get go back then. The automatics of today have very little slippage, but slippage is still a factor.

This same type of slippage is present in the 545 SMG. The OBC is doing the mating during the start up and it is designed to take care of the electric/hydraulic clutch. So, the engine is turning proportionately more than the drive wheels are. Since the clutch cannot be controlled manually, the amount of slippage is higher than with a manual. If the explanation I have given is correct, we should expect the SMG clutch to last longer than a manual clutch since engagement is managed by the OBC. Since I easily get more than 100,000 miles on a manual clutch, I am expecting a trouble free ride out of my 545 SMG for years to come.

bmwin14rsm

In regards to SMG, I feel I have a good story about it. I ordered a 545 with SMG August 2004. It had many problems, and finally ended up with BMW buying the car back. I loved the SMG so much, regardless of the problems, I reordered another SMG. With the new SMG, I haven't had any problem with it.

SMG is great, even my wife can drive the car with the enthusiam of a manual. (She can't drive a stick to save her life).

EBMCS03, from what I have read on the Audi's system vs. BMW's system is the BMW's single clutch system is actually quicker in the double down shifts than the Audi. Audi's system is faster on the single down shift than the BMW's since the Audi's system already has the pressure of the 2nd cluts on the next gear. But when it comes to down shifting two gears, which is what you typically need when getting out of a hole, the BMW is about 2 times faster than the Audi's. I can't remember where I got this information, but I remember it was an automotive trade magazine rather than the typicall automotive main streem mags.

markt540i

SMG drivers: do you ever lose track of what gear your in?

Using the steptronic (I am driving an e39 steptronic), I feel more out of touch than with a manual and have concerns about this relative to getting an SMG transmission. The SMG matched rev downshifts are awefully tempting though. I am leaning toward a manual if they offer it in the 550 soon enough. With a manual tranmission (3 series) I never lost track of what gear I was in. Its like I could feel the torque through the shift lever and tell what gear I was in or needed to be in as well as being able to feel what position the shift lever was in to know what gear was engaged. Maybe the action of having to shift constantly makes one more aware or connected since the manual transmission won't shift for you.

Do you feel that same connection with the SMG or do you feel like you give that up with SMG? Or does this make absolutely no sense at all?