i should clarify my statement above when i drove a manual car i downshifted when when coming to a stop. I did this so that the engine is engaged if i need to accelerate or traffic started moving again.

 

Nope, that's the one that uses regenerative braking right?

What I was thinking was that the braking that happened when I downshifted on the test drive felt too strong to be just engine braking. To me it felt more like the actual brakes simulating engine braking. That's just what it felt like to me though, if you tell me I'm wrong then I believe you.

 

Interestingly enough, the IS350 senses pitch and will downshift for you if you are going down hill. I have seen this most recently here in my new home while going down a relatively steep hill. Apply brakes, see immediate downshift to control speed.

There is a pretty extensive write up in the New Car Features about this.

 

Thats cool! What about the IS250? Does it do that?

 

the is250 will do that as well. Most of all the new cars will do this. I do not know if the car sense pitch rather it downshifts to maintain a certain speed. Your engine was to work harder to maintain a constant speed when traveling upwill therefore it will downshift to compensate for that.

 

counterpoint: broken transmission is covered by warranty, worn brakes are not.

in any case, downshifting is not going to prematurely wear out the transmission. i use the brakes but feel free to use a combination of both or simply the brakes.....doesn't matter.

 

I think its worthless to down shift even though I do it lol it decelerates slow to save gas for people who like to play with the gas and can't keep a steady foot.. Besides the car downshifts it self too

 

I tend to agree, unless you're revving to redline with a downshift, I can't think that braking with the foot and a little down shift can hurt.

 

Braking and downshifting isn't bad per se. Downshifting instead of braking is bad. It sucks oil up past the rings, puts unnecessary high tensile loads on the rods, wears the clutch harder, or in the case of an automatic, unnecessarily raises the fluid temperature and stresses the Sprague clutches unnecessarily. Fine to downshift in combination with braking. Not fine to downshift instead of braking.

Counterpoint isn't a point. If the transmission survives warranty and breaks 6 months later from abusive use, you will not get anything under warranty. If you are a disposable society type and expect to replace your car before the warranty is expired, then you can happily pass on your problems to the next unsuspecting owner. You're still paying the price by needlessly replacing a device that serves your purpose because you are afraid your abuse will render it unserviceable before its time. So you are investing your money in another one when you could be enjoying the benefits of ownership and spending your money on something else.

 

I can't imagine anyone would avoid brakes altogether?

Is there a maximum rpm one should avoid when downshifting? In other words, would 500rpm or 1krpm be too drastic, on a downshift?

 

If you're driving an automatic, just let the transmission do the downshifting if you are driving on the street. There's no set rpm, and Toyco programmed it to be as nice to itself as possible.

If you're on the track, you don't need to be asking me this question because you should already know what you are doing with the gearbox (and you know your service life will be less than low stress street use.)

I've known people with manuals who will downshift mercilessly from very high rpm instead of braking harder. It's just not good if you want a long service life from your drivetrain. That's the point of what I'm saying. Brakes are cheap. Drivetrains are not.

 

Counter counter point... Downshifting WILL wear out the transmission faster. Faster movign parts equals more friction which equals more wear and tear, period. it is however a slow enough process that when you start seeing the negative effects, you will no longer be under warranty.

 

Is there much difference on the stress to the tranny between aggressive down shifts and aggressive up shifts?

 

Heh, I think this is the second time I've seen you bring up this "New Car Features" section. You said this is on Lexus' page, right? Where is it? I can't seem to find it.

 

Only time I downshift to slow down, is if I see law enforcement