Fizzboy7

I have yet to see an advantage to this. When I am cruising at 70 mph in auto mode and want to downshift for braking, I don't want my car going from 6th to 4th. Any idea on why Lexus programmed it this way? TIA

Namir

Down shifting is done to put the engine at higher RPMs so you can be in the power band, and thus accelerate faster, ie for passing.

Brakes are for braking.

carchitect

iTrader: (1)

Its just a design characteristic. If you were going a lot higher rate of speed where 4th would be out of range, the sport mode switch over would drop you into 5th. Needless to say, if you were running a cannonball and topping the car out, going to sport mode will leave you in 6th. I have yet to try out the last one and ,quite frankly ,don't think I have the need to do so.

Lexus more than likely set it up this way to make the operator of the vehicle realize that sport mode is designed for performance. Its a Dr.Jkyll & Mr. Hyde thing, ya know.

-Joe

Fizzboy7

Interesting. You've heard the dropping to 5th and 6th gear thing from others or?

Fizzboy7

That's a 50% effort. Shifting should be for braking too.

blk_is300

I'd rather wear down my brake than my gears since brakes are so much cheaper to replace. Our IS's automatically downshift to 4th gear for you whenever you apply brakes while going downhill, but I always shift into 5th to avoid too much engine wear... I live on a hill and I need to drive 4 miles downhill everyday.

sungyc

iTrader: (1)

sometime mine switch to 3rd gear directly...@_@ dont really remember in what condition it does that though... one of the hills.. up or down...@_@

ndk83

I can vouch for that, i do alot of highway driving at highspeeds, ive dropped it a couple of times and it drops to 5. Having seen it drop in at 6 (maybe once but cant confirm) Its a smart tranny and i use it all the time for engine breaking. While i doubt this will cause me any problems cant say the same bout the cars future owner though lol.

Fizzboy7

I don't think one can wear down a transmission shifting from 6th to 5th or even 4th. A modern day trans should be able to handle such a load (hence the default to 4th). Plus the Lexus nannies will kick in anyway and not allow the shift if it's too soon.
What sparked my question relates to smooth driving. If driving in manual mode, it's impossible to downshift on the freeway w/o making it known to your passengers you have to alter your speed.

ndk83

F##k the passengers!!!

Fizzboy7

LOL!! Some passengers get special treatment, ya know? ; )

4TehNguyen

iTrader: (1)

downshifting increases wear on your engine and drivetrain components because the RPM is suddenly changing. Buy new tires if you want to increase your braking power

It goes to 4th gear because if I want to pass someone and I change to manual mode, it would be stupid if it stayed in 6th and then I have to paddle down twice to be able to pass

wkw84

your mother, right?

Namir

I respectfully disagree.

blk_is300

In the view of physics, stopping/slowing down the car with engine braking means putting (car mass)x(deceleration) = (Stopping Force) onto your powertrain. I would use engine braking for an MT since it uses a clutch instead of a torque converter, and generally a clutch is able to handle more torque than a TC. If you ask your mechanic, I believe he'll tell you the same thing.