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My wife and I are very happy with our CT. She said she noticed a slight "surge and release" while she was driving it home (like pushing the accelerator and releasing - even though she wasn't). She thinks it may have just been when she was in Sport mode, but isn't certain. It did happen several times during the 20 minute ride.

I drove it and didn't really notice anything, but since this is her car I want her to be 100% happy. Are there things I should ask her to check/look for to understand what may be going on? Is this something to do with handling characteristics of hybrids?

AS ALWAYS, TIA
 

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Is it possible that she was coasting downhill and when it reach certain speed, the engine came on? The engine will come on when you reach certain speed (around 35 I think) even when you don't really need it going downhill.
 

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Discussion Starter #3
Is it possible that she was coasting downhill and when it reach certain speed, the engine came on? The engine will come on when you reach certain speed (around 35 I think) even when you don't really need it going downhill.
Thanks for the quick reply. She say's that's possible; she was on a slightly hilly and curvy road. The road is posted 45 MPH speed. We're going out today and I'll be more "atuned" to it. (If I can get her to let me drive, of course!! LOL) Thanks again.
 

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I think there's a couple of these surges from what I've observed :

Normal -> Sport mode

When you select Sport mode from Normal/Eco, it's possible for a CT to accelerate when you slacken off the throttle a little. That's because the throttle response is higher in Sport ... Working As Intended but it's something every CT owner needs to know about in case it catches them out (would only lead to dents if you're tailgating ... lol)

Low speed handover between electric brake and mechanical brake

Lots of people have commented on this one. The CT does so many things so well with the handover between engine, electrical and mechanical but there are a couple of gaps ... Low speed behaviour is one of them :

If you're slowing down to a stop, the car will try and harvest as much energy as it can up to a certain point :

Normal speed -> 7mph - grab as much energy into the electric as possible
Normal -> 7mph heavy braking - use the mechanical brakes to help out
(we have awesome braking available when we need it)
7mph -> stop - mechanical brakes only

It's that transition from electrical to mechanical braking at about 7mph where the surge is supposed to happen. You can feel it in your tummy, like a "perceived" acceleration when you know you're slowing down. I suspect it's the car changing from 100% electric brake -> 100% mechanical brake. There's possibly a little lag there which makes it feel strange ...

But - feels less strange when you think - "ok, I think I know where this is coming from now" and "hey, it's slow speed only and I still have lots of time to react" :) and "I'm still gonna stop in time" :D

It's an artifact of the drive-by-wire systems where the software isn't quite 100%. Takes good awareness to spot it :).

Concern ? Nah. After having a complete brake failure in a normal car, I quite like having 2 wholly independent braking systems :D (actually 3 with B-mode). And the electric side takes enough load away from our mechanical brakes that they'll be there when we need them.
 

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Thanks for the quick reply. She say's that's possible; she was on a slightly hilly and curvy road. The road is posted 45 MPH speed. We're going out today and I'll be more "atuned" to it. (If I can get her to let me drive, of course!! LOL) Thanks again.
Oh ! Misread where the surge might be happening :)

Engine is set to come on at about 45mph actual road speed, to stop the electric from going overspeed. When it does, the "EV" light indicator will turn itself off.

Takes good awareness to spot that changeover too :)

I found another one while on our motorways (70mph limit). The normal cruise rpm is 2000 at 70 (indicated). However, if the car is going down enough of a slope to maintain that without the engine, it'll rock the engine back to 1000rpm idle. I think it's effectively freewheeling ... Trouble is, that transition isn't very subtle ! :D

And you can probably guess that for the next few drives along that road, Engineer Geeky Techy Nerd (me!) was looking for as many excuses as possible to trigger that 2000-1000 rpm transition again :cool: (Toy does something New - must play !)
 

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Discussion Starter #6
Oh ! Misread where the surge might be happening :)

Engine is set to come on at about 45mph actual road speed, to stop the electric from going overspeed. When it does, the "EV" light indicator will turn itself off.

Takes good awareness to spot that changeover too :)

I found another one while on our motorways (70mph limit). The normal cruise rpm is 2000 at 70 (indicated). However, if the car is going down enough of a slope to maintain that without the engine, it'll rock the engine back to 1000rpm idle. I think it's effectively freewheeling ... Trouble is, that transition isn't very subtle ! :D

And you can probably guess that for the next few drives along that road, Engineer Geeky Techy Nerd (me!) was looking for as many excuses as possible to trigger that 2000-1000 rpm transition again :cool: (Toy does something New - must play !)
I read your replies to my wife and based on her nods and "sounds right" she's thinking it's just normal behaviour. She also said being brand new, she's probably over sensitive. We thank you for all the thought and time to reply. (I'm the tech-geek, and am blown away by all the gadgets). Thanks again.
 

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:D I think it's the brain going "something strange is happening that I didn't expect - should I worry ?" with potential answers being :

"Nope - don't understand, ask garage" and
"Ah ha ! It's the car turning the engine back on"

I've asked passengers about that 45mph thing and the whole engine turning on and off on its own and they've barely noticed it. It's a credit to Lexus that while it's noticeable, it takes good awareness to spot it. It'll be from the car spinning up the engine to the correct rpm before sending any fuel through it, that'll cause a little lurch.

But definitely better than if I'd been trying to do something similar in my last cars with their manual transmissions and clutches :D

PS Being sensitive about what the car's doing is not a bad thing - like spotting that a turbo diesel car is down on power early means it could be a cheap repair rather than a "oh eck I need a new turbo" :cool:
 
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