Toymota

It does this when you are going downhill. Because you touched the brakes, the car thinks you want to slow down, so it downshifts to give a bit of engine braking to save your brakes. Generally, if you release the brakes and don't touch the gas, the car will not pick up speed nor slow down in this mode. If you do want to speed up, press the gas and it should leave this mode and shift back to 6th gear, though I don't really remember because I live in Florida and there are no hills for me to try here.

Gas consumption should be the same in 5th or 6th gears, that is, close to zero because you are engine braking.

Also, do not put the transmission in neutral. Engine braking also produces a lot of vacuum which is used by the power brake assist.

cwtt

Yes I think it is unnecessary. I think there may actually be something wrong which is why I posted this question.

When did I ever complain about gas mileage? I could care less. Its a Lexus not a Prius.

I'm concerned because there is no reason to be cruising on a flat level freeway doing 65-80mph at a steady speed with the car stuck in 5gh gear. I'm talking about going for several miles before it will finally up-shift to 6th. (No hills or inclines involved).

I'm beginning to wonder if my TPS is off or miss calibrated.

sr20mofo

iTrader: (10)

mine does this if im on a down hill and or when the car is still warming up. nothing but a reset ecu should solve your scenario.

chikoo

Maybe u have a history of accelerating after u brake and the car has learned that over time.

B16da9

iTrader: (7)

From my experience of driving/riding my sisters (Auto) IS250 I think something is wrong. Hers shift into 6th gear once she gets up to highway speed without a problem and this also applies even we she or I tap on the brake and get back up to highway cursing speed.

jgr7

iTrader: (1)

My 2012 IS350C also does this and has since new. It will do it on flat ground when going hwy speeds and have to touch the brakes for a slow down and it does it in the mountains under the same brake touch slow down. In the mountains it seems to hold in lower gear much longer than on flat ground. Sometimes in the mountains I put in S mode and paddle to 6th to fix this.

brociouz

iTrader: (65)

Not necessarily. Sport mode effectively resets the ECU's throttle mapping to default, so if the problem is that the car "learned" this extended 5th gear behavior, going into sport mode would be a (workaround) fix.

Hoovey689

iTrader: (16)

this happens to me every now and then. Stock I don't care much, but with a exhaust and midpipe oh jeez

people near me probably think i'm trying to race them

smokyis350

iTrader: (21)

+1.. I'm more worried about cops than people thinking I'm trying to race them.

Slammer1

Mine has done this since I've owned it, but never really worried about it. Anyone have their cars do the opposite? When I am rolling down a hill at around 35-45 mph, the car shift up (seemingly unnecessarily) to a higher gear. Almost like it wants to "coast". When I step on the gas again, it will go back into the gear I was in. The gear that it shifts up into isn't correct for the relatively low speed, and it would be in a gear that high if I were travelling on a flat road. Just curious. I will try to duplicate it soon and pay attention to exact speed and gears involved.

nosurprise

iTrader: (1)

My car is very predictable. It will always go to 6th when it hits 40mph unless I'm accelerating hard. It will go to from 6th to 5th when it drops below 40mph (unless I'm coasting in which case it will stay at 6th until 35mph). It also goes to the 5th if I step on the gas pedal relatively hard -- not the brakes (unless I step on the brakes hard). It always go back to 6th from 5th in a few seconds when i'm not applying heavy pressure on gas or brake.