Shift Lag?
When I use the paddle shifters, I just shift earlier than I really want to.
I've had one brief, and very impressive drive (albeit not 'perfect') of an IS250, and had no problems with either the paddles or the floor shifter re 'manual/sequential' mode.
I've driven most of the latest BMW's with the exception of the M series, and without doing an A/B I'd say the 'lag' is about the same.
On the Bimmers with their ZF autos, they all via the linked Engine ECU/transmission, slightly retard the timing on the change up, so as to reduce engine torque and hence shift shock. I should imagine that the Aisin unit fitted to the IS Lexus models would be at least the match in terms of refinement of electronic shift control, and hence results.
Obviously if you have your foot well planted, and the engine is putting out full, or near enough full power, the shift will be fractionaly slower than when cruising on a light throttle; again to soften shift shock - certainly all the Bimmers I've driven do that.
One exception I found was with Mercs; they of course do design and build their own gearboxes in-house; all of the new ones I've driven lack the smoothness of the ZF autos in the BMW's when driven under kickdown/full power/acceleration mode; But with a faster, albeit jerkier change. Take ones pick I guess.
Personally I find with a combination of using either paddles, or the sequential mode of the floor shifter in combination with left foot braking, one can get a great deal of control and satisfaction when pushing on in ones driving during more, er, enthusiastic moments. True, not quite as satsifying as heel and toeing manual changes in a true manual, but very satisfying nonetheless.
Fully robotised SMG manuals, such as the BMW box, with electronics/hydraulics controlling an otherwise conventional manual gearbox, will have the fastest changes, and best performance, but usually they're not very smooth either; I've certainly read of a few BMW M5's being towed away after using the launch mode broke the transmission!
The best all-round auto/sequential robotised manual setup I have found is the Volkswagen DSG gearbox used in the Golf GIT, the new Jetta, and of course in the Bugatti Veyron (not likely to ever get to drive one of those!) when performance is the issue, combined with smoothness.
However a 'conventional' epicyclic gearbox with torque convertor as used in the IS250 is still the best compromise if smoothness, coupled with some manual control is the desired outcome, which I guess is where Lexus are coming from, i.e. the IS250 is a luxury vehicle with a sports feel/driving balance.
Best
John..
Celebrating Lexus & Toyota from Around the Globe
I've had one brief, and very impressive drive (albeit not 'perfect') of an IS250, and had no problems with either the paddles or the floor shifter re 'manual/sequential' mode.
I've driven most of the latest BMW's with the exception of the M series, and without doing an A/B I'd say the 'lag' is about the same.
On the Bimmers with their ZF autos, they all via the linked Engine ECU/transmission, slightly retard the timing on the change up, so as to reduce engine torque and hence shift shock. I should imagine that the Aisin unit fitted to the IS Lexus models would be at least the match in terms of refinement of electronic shift control, and hence results.
Obviously if you have your foot well planted, and the engine is putting out full, or near enough full power, the shift will be fractionaly slower than when cruising on a light throttle; again to soften shift shock - certainly all the Bimmers I've driven do that.
One exception I found was with Mercs; they of course do design and build their own gearboxes in-house; all of the new ones I've driven lack the smoothness of the ZF autos in the BMW's when driven under kickdown/full power/acceleration mode; But with a faster, albeit jerkier change. Take ones pick I guess.
Personally I find with a combination of using either paddles, or the sequential mode of the floor shifter in combination with left foot braking, one can get a great deal of control and satisfaction when pushing on in ones driving during more, er, enthusiastic moments. True, not quite as satsifying as heel and toeing manual changes in a true manual, but very satisfying nonetheless.
Fully robotised SMG manuals, such as the BMW box, with electronics/hydraulics controlling an otherwise conventional manual gearbox, will have the fastest changes, and best performance, but usually they're not very smooth either; I've certainly read of a few BMW M5's being towed away after using the launch mode broke the transmission!
The best all-round auto/sequential robotised manual setup I have found is the Volkswagen DSG gearbox used in the Golf GIT, the new Jetta, and of course in the Bugatti Veyron (not likely to ever get to drive one of those!) when performance is the issue, combined with smoothness.
However a 'conventional' epicyclic gearbox with torque convertor as used in the IS250 is still the best compromise if smoothness, coupled with some manual control is the desired outcome, which I guess is where Lexus are coming from, i.e. the IS250 is a luxury vehicle with a sports feel/driving balance.
Best
John..

this is concerning the is350, not the 250. the 250 comes in manual whereas the 350 does not. also, no matter what speed youre going with the 350, the shift lag is still present and noticeable.
Thanks... I am under the understanding that both IS250 & IS350 use the same Aisin sourced 6 speed auto, which is why I commented upon my personal impressions.
However I would accept that given the greater power of the IS350 engine, the ECU programing could be different. As far as trying to compare lag between say an BMW 3 series, with an ZF auto, and an Lexus IS250/350 with the Aisin auto, IMHO if you want to compare as accurately as possible, you would need identical road and driving conditions, and a stop-watch to accurately compare; all else is purely subjective IMHO.
As I say, the lag between the many BMW's and the one Lexus auto I have driven seems subjectively the same; but of course that's just an impression - side by side comparos with a stopwatch may reveal a different result - but again the only way I can think of to get an accurate and fair picture - not one based on different road and traffic conditions, different accelerator positions (with electronic throttle control, the ECU programing/response will be different) and different driver opinions, is to accurately measure it (the lag).
Just my 2c worth..and IMHO of course...
Best
John...









