Lexus IS-F or BMW M3 WITH DCT LAG?

[Damage Inc]

Originally Posted by tmaung

. If you like nicer interior and more luxurious (and a bit more reliability), then the F

I wouldnt say the interior of the F is more luxurious than the M3 but the opposite. I would argue the BMW feels more upscale as the Lexus uses quite a few Toyota bits.

[gr8000]

How does the M3 compare to the IS-F? You are joking right?

Go for the M3. Do yourself a favour and go try the DCT. It is brilliant!

[09E92M34ME]

not even close. M3 FTW

[DevJ]

Originally Posted by tmaung

I have the Lexus IS350. I know it is not the F but I see some refinement over the M3 in some ways. I feel the M3 is a great handling car and may not be the fastest of the group (F, C63). It really depends on what you are looking for. If you want the fastest 0-60, I would probably go with C63. If you like driving twisty roads, then the M3. If you like nicer interior and more luxurious (and a bit more reliability), then the F. However, I don't think they are upgrading the Nav system on the F, only on the IS350 convertible, so I would wait until they do the hardware upgrade.

+1, Well stated

[swamp2]

Originally Posted by PowerLex

If you are in M mode, which you would use on the track, it disengages the torque converter. The car acts like a true manual at that point, only upshifting downshifting when you shift. The only exception is that it downshifts as you come to a stop to prevent stalling. There is no lag whatsoever.

News to me that the M-DCT has a torque converter.

[sayemthree]

I would say if you have to ask then you deserve the Lexus.

[330CIZHP]

Originally Posted by swamp2

News to me that the M-DCT has a torque converter.

He means the IS-F transmission. I saw the chief engineer of IS-F explaining that as well.

Still, that begs the question, if it is that easy to make a lock-up torque converted automatic to behave like a manual by just shutting off the torque converter, why did BMW go through the hassle of putting double clutches when they could have achieved that my shutting off the torque converter whenever required.

[Epik]

In all honesty the ISF is a pretty great car. I prefer the M3 exterior styling, Lexus is better put together, but other than that it's pretty close.

[RealSanaii]

Originally Posted by Epik

In all honesty the ISF is a pretty great car. I prefer the M3 exterior styling, Lexus is better put together, but other than that it's pretty close.

I don't like how it looks, inside and out.

[swamp2]

Originally Posted by 330CIZHP

He means the IS-F transmission. I saw the chief engineer of IS-F explaining that as well.

Still, that begs the question, if it is that easy to make a lock-up torque converted automatic to behave like a manual by just shutting off the torque converter, why did BMW go through the hassle of putting double clutches when they could have achieved that my shutting off the torque converter whenever required.

Hmmm, I guess that makes you confused about "M mode" as well which is a BMW thing, not a Lexus thing. I guess it could just be a poor choice of lingo... either way a pretty glaring error.

Modern locking automatics are pretty darn nice. The manual modes are great, the losses due the torque converter can be minimized and they have good full manual modes. The limitations of them compared to a DCT are: weight, lack of precise control over gear ratios, complexity, shift times (small advantage to DCs) and losses. These are generalities and not every DCT exceeds every auto in each limitation.

[southlight]

Originally Posted by swamp2

Hmmm, I guess that makes you confused about "M mode" as well which is a BMW thing, not a Lexus thing. I guess it could just be a poor choice of lingo... either way a pretty glaring error.

He's probably talking about the manual mode of the IS-F's auto which is selected by putting the center console shifter in "M", so talking of it as "M mode" seems legit to me.


Best regards,
south

[Driver72]

Originally Posted by swamp2

Hmmm, I guess that makes you confused about "M mode" as well which is a BMW thing, not a Lexus thing. I guess it could just be a poor choice of lingo... either way a pretty glaring error.

Modern locking automatics are pretty darn nice. The manual modes are great, the losses due the torque converter can be minimized and they have good full manual modes. The limitations of them compared to a DCT are: weight, lack of precise control over gear ratios, complexity, shift times (small advantage to DCs) and losses. These are generalities and not every DCT exceeds every auto in each limitation.

Just to be clear here, a DCT weighs more than a traditional automatic.
The auto in the 335i weighs a mere 11 lbs more than the manual. However, IIRC the DCT weighs about 60 lbs more than the manual in a M3.

I'm confused by what you mean "lack of precise control over gear ratios" and "complexity" when describing the limitiations of an auto compared to a DCT however. Sure some autos will automatically shift for you at redline, which is a curse at times, but a blessing at others) but there are regular autos that won't do that and just bounce off the rev limiter like a DCT.
That's mostly about the software mapping.

I personally think the DCT offers these advantages:
1. Slightly faster shift times than traditional auto (and I mean SLIGHT) like .01-.02 seconds. Autos shift pretty darn fast these days.
2. Less drivetrain losses. But to be honest, I don't even know if that is much either. In many, many dyno tests of the 335i the manual tranny cars only do about 5 rwhp/5rwtq more than the autos do. So again, somehow the autos seem to be getting more efficient these days too.
I don't think it's possible for a DCT to be more efficient than a traditional manual when it comes to drivetrain losses.


It's hard to say really if DCT's offer much more of an advantage than a very good automatic these days.
If you were to take two identical cars, both with 7 speeds, one a traditional auto the other a DCT, with the same gear ratios and final drive ratio, I think there would be little difference between them performance wise.
The DCT would probably weigh 40-50 lbs more, but it's slight shift speed and slight drivetrain loss advantage would probably cancel that out.
But overall, I'd bet they'd be within .1 second of each other in a run from 0-120 mph.
I'd give the slight edge to the DCT though as even if it got 1% better drivetrain losses and shifted .01 seconds faster, it would still give it a slight edge even with it's slight weight penalty.

As for the OP: I agree, just go drive both cars and make your choice from that.
I'm guessing personal styling likes as well as insurance costs, dealer location/reputation, etc as well as the dealers willing to negotiate will play a part in your decision as well.
Unless you are in the 1-2% of owners who will track the car, in that case just get the M3. If you are in the 4-5% who will drag race the car, I'd put my money on the IS-F by a bit stock, and the IS-F is probably easier and cheaper to mod too.

[330CIZHP]

Add to that, in my opinion, automatics lose their responsiveness lap after lap of extensive hard driving due to heat and stress. The M-DCT might be superior in giving more consistent performance after hard use over extended periods of time.

Also, M3 is a high-revving car and I think an automatic transmission is not very good at handling stress and heat of high-revs over extended periods of time.

That is what I think is the reason why BMW did not put an automatic in an M car recently. E36 M3 was the first and last one.

Originally Posted by Driver72

Just to be clear here, a DCT weighs more than a traditional automatic.
The auto in the 335i weighs a mere 11 lbs more than the manual. However, IIRC the DCT weighs about 60 lbs more than the manual in a M3.

I'm confused by what you mean "lack of precise control over gear ratios" and "complexity" when describing the limitiations of an auto compared to a DCT however. Sure some autos will automatically shift for you at redline, which is a curse at times, but a blessing at others) but there are regular autos that won't do that and just bounce off the rev limiter like a DCT.
That's mostly about the software mapping.

I personally think the DCT offers these advantages:
1. Slightly faster shift times than traditional auto (and I mean SLIGHT) like .01-.02 seconds. Autos shift pretty darn fast these days.
2. Less drivetrain losses. But to be honest, I don't even know if that is much either. In many, many dyno tests of the 335i the manual tranny cars only do about 5 rwhp/5rwtq more than the autos do. So again, somehow the autos seem to be getting more efficient these days too.
I don't think it's possible for a DCT to be more efficient than a traditional manual when it comes to drivetrain losses.


It's hard to say really if DCT's offer much more of an advantage than a very good automatic these days.
If you were to take two identical cars, both with 7 speeds, one a traditional auto the other a DCT, with the same gear ratios and final drive ratio, I think there would be little difference between them performance wise.
The DCT would probably weigh 40-50 lbs more, but it's slight shift speed and slight drivetrain loss advantage would probably cancel that out.
But overall, I'd bet they'd be within .1 second of each other in a run from 0-120 mph.
I'd give the slight edge to the DCT though as even if it got 1% better drivetrain losses and shifted .01 seconds faster, it would still give it a slight edge even with it's slight weight penalty.

As for the OP: I agree, just go drive both cars and make your choice from that.
I'm guessing personal styling likes as well as insurance costs, dealer location/reputation, etc as well as the dealers willing to negotiate will play a part in your decision as well.
Unless you are in the 1-2% of owners who will track the car, in that case just get the M3. If you are in the 4-5% who will drag race the car, I'd put my money on the IS-F by a bit stock, and the IS-F is probably easier and cheaper to mod too.

[grayshrk]

Originally Posted by Driver72

...and the IS-F is probably easier and cheaper to mod too.

Depends on what you mean by "mod". If we're talking tuning the car, there are very few options right now for tuner supplied IS-F mods. My friend has an IS-F, and all he's been able to find in the way of mods are an exhaust and intake. There may be more out there, but definitely hard to find.

[sayemthree]

they build a better Camry too!!!!

[zenderm3]

Originally Posted by tightie

You're on a M3forum.. come on now.

lol - so true. IS-F is certainly a luxury sports car. The M3 is a true Sports Performance Car. Totally demolishes the IS-F when it comes to its pedigree. IS-F, C63 both copies of the concept of the M3!

///M3 is the rule

[swamp2]

Originally Posted by southlight

He's probably talking about the manual mode of the IS-F's auto which is selected by putting the center console shifter in "M", so talking of it as "M mode" seems legit to me.

My bad, looks like I've been totally wrong on this.

PowerLex: Sorry about that.

I'm pretty shocked the IS-F calls one of its modes M mode but I guess M is for manual not Motorsport...

[swamp2]

Originally Posted by Driver72

Just to be clear here, a DCT weighs more than a traditional automatic.
The auto in the 335i weighs a mere 11 lbs more than the manual. However, IIRC the DCT weighs about 60 lbs more than the manual in a M3.

That is apples to oranges as it is 6 speed vs. 7 speed. Here is another apples to apples comparison (but more appropriate) because it is directly IS-F vs. M3). IS-F transmission weight: 211 lb. Getrag 7 speed DCT: 156 lb. Another reason this is not apples to apples is that I'm pretty sure BMW uses a different housing than Getrag so the weight figure is not really for the exact M-DCT unit. I'm sure it is close though.

Originally Posted by Driver72

I'm confused by what you mean "lack of precise control over gear ratios" and "complexity" when describing the limitiations of an auto compared to a DCT however.

When you use a plantary gear sets the ratios of the gear ratios is fixed accorinding to a predefined sequence. Hence if an engineer wanted a 1.105 to maximize performance he might only be able to obtain a 1.012 (made up numbers to make the point). Read up on planetary gears.

Complexity is based on the number and diversity of the part count in autos: planetary gear set, bands, wet clutches, hydraulic system for bands and clutches, a pump for the fluid, etc.

Originally Posted by Driver72

I personally think the DCT offers these advantages:
1. Slightly faster shift times than traditional auto (and I mean SLIGHT) like .01-.02 seconds. Autos shift pretty darn fast these days.
2. Less drivetrain losses. But to be honest, I don't even know if that is much either. In many, many dyno tests of the 335i the manual tranny cars only do about 5 rwhp/5rwtq more than the autos do. So again, somehow the autos seem to be getting more efficient these days too.
I don't think it's possible for a DCT to be more efficient than a traditional manual when it comes to drivetrain losses.

I am not aware of any DCT that shift in 10-20 ms. I think 30 is a better minimum number for the best units. Shifts in a DCT vary in length based on which gears are being changed and other variables.

Auto absolutely have evolved to lower and lower losses. The locking torque converter is a big part of that. Current wet clutch DCTs like the M3 will have more losses then the next gen dry clutch units (actually already released by VAG IIRC). But either way the added complexity of a DCT over a traditional manual will always produce slightly greater losses (again apples to apples). In general the ranking for losses will be:

Manual < dry clutch DCT < wet clutch DCT < torque locking auto < traditional auto.

Originally Posted by Driver72

It's hard to say really if DCT's offer much more of an advantage than a very good automatic these days.
If you were to take two identical cars, both with 7 speeds, one a traditional auto the other a DCT, with the same gear ratios and final drive ratio, I think there would be little difference between them performance wise.
The DCT would probably weigh 40-50 lbs more, but it's slight shift speed and slight drivetrain loss advantage would probably cancel that out.
But overall, I'd bet they'd be within .1 second of each other in a run from 0-120 mph.
I'd give the slight edge to the DCT though as even if it got 1% better drivetrain losses and shifted .01 seconds faster, it would still give it a slight edge even with it's slight weight penalty.

Most of this "conclusion" had been well refuted above. In an apples to apples comparison on weight, simplicity and performance DCT will offer a slight edge over the best automatics. That being said the advantages will indeed be very slight compared to the best modern high performance autos.

[E90///M3`]

Originally Posted by GatorBlue371

Get the C63 or M3 6speed.


The AMG is more exciting than the M, and the M is more a drivers car.

i prefer the M3 over the IS-F but if the comparison was made as GatorBlue said.... C63 FTW!

[Remonster]

Originally Posted by E90///M3`

i prefer the M3 over the IS-F but if the comparison was made as GatorBlue said.... C63 FTW!

I'm with you two, the C63 shouldn't be overlooked if you can't be bothered to shift for yourself. The IS-F has too many gears and in normal usage is constantly changing its mind, the C63s auto was clearly superior to me after driving it last week and the sound it makes is much better than the IS-F. The handling wasn't even comparable, the AMG felt both more nimble and much more comfortable.

Even when I ignore my BMW bias, the M3 still seemed like a much better car than any of its competitors, it's just in a completely different league. I don't particularly like the M-DCT, it's better than SMG was and I actually prefer it to the autos in the IS-F and C63 but I wouldn't even think twice about getting the M3 with the 6 speed manual. If you definitely don't want a manual, the M3 is still my top pick.

[PowerLex]

Originally Posted by swamp2

My bad, looks like I've been totally wrong on this.

PowerLex: Sorry about that.

I'm pretty shocked the IS-F calls one of its modes M mode but I guess M is for manual not Motorsport...

I didn't even realize I wrote that actually until I just rechecked this thread. I wouldn't say it is a "M" mode. As far as "modes" go on the ISF there is normal, snow, and sport. The "M" would classify as simply the gear shifter selection. You have the typical gears and then an M for the manual paddleshift mode which as some other people explained.

I believe on the IS250 and IS350, the alternate shift mode is designated as an "S" because it is a traditional tiptronic or whatever you want to call it.

Explaining little things like that via typing is a Pain in the a$$.

[warzilla]

My friend just got the IS-F (was trying to convince him to get the M3 sedan with DCT). Basically he needed something that was fast, had four doors and some auto-like transmission.

He saw a IS-F at CarMax and went for it (he also has a RX-400 so he was familiar with the Lexus brand -- ie the nav system, drive, etc). I stopped by his house the other day to see his new car and also go for a spin. He also drove my M3 as well (he never drove it before, maybe I should have let him before he brought the IS-F...as you will see in my story).

So we first took out his IS-F. First impressions, looks great, nice wide fenders, wheels/tires look great. IS-F has the same size rear tires as a M3 with the 19' inch rim option. Fronts are 225/40/19 compared to M3's 245/35/19.

Got inside and looked around. Except for the light-color carbon fiber trim, some F badges, looked very similar to most IS cars. Steering wheel was very thin, or maybe I'm too use to the beefy steering wheel on the M3. It felt like a toothpick with leather wrapping.

So took the car out and immediately tried the manual shifting with paddles. Car was a bit 'soft' until you got over the 4000rpm mark and then you notice the 'bite' of the v8 and also hear the wonderful exhaust sound (very nice exhaust sound as everyone says). But overall was not impressed with the drive. It had what I call the "lexus" feel. Anyone who drove a lexus, you know what I mean, a silky smooth feel that is conveyed on every piece of the car including the steering and transmission. I asked for the 'power/sport' setting, which is hidden behind the steering wheel and near the ignition 'on/off' button. Now the car got more interesting. Not sure but I believe the 'sport' setting gives more throttle response and I was actually getting some more wheel hop (roads was a bit slick from rain before). But overall, felt the car was very lexus-sy and soft down low, with the robust V8 hiding until you start really hammering the throttle.

Then we went into my M3. First I let my friend drive it in my normal settings (EDC on comfort, MDM off, power off, DCT at S4, etc). He's not really into the paddle shifters so was driving the car in an auto mode. He felt how 'raw' the car was compared to his IS-F right away. Then after a few blocks I told him to stop. I explained the "M" button and how it has my options saved (EDC on sport, MDM on, power on, DCT on S6, steering on Sport, etc), and told him press the 'M' button and then drive. He was then like 'whoa', he got the M right then and there. Afterwards we got back to his house and he basically asked me all about the car including the carbon fiber roof (he asked why I didn't have a sunroof). Then he started staring at my car for a bit. I kid you not, I think he regretted right then and there in not getting the M3.