zes

As I have been getting a bit more experience with my 300h I notice that a couple of things about its performance are not Lexus like:
1) When the ICE idles, it does so at about 1200 rpm to charge the traction battery. At that speed it sounds buzzy when the car is not in motion.
2) if I step on it from rest, and the ICE kicks in the moment the car starts moving, I can sometimes feel a slight jolt which I feel is unbecoming a Lexus.

Here is how I would like the car to behave:
1) when the car is idling, the rpms should be around 600 or so. From prior experience I know that the engine will be very smooth and quiet then. I know you will say that at that speed the engine will not charge the traction battery. Well I don't care. If it costs me an mpg or two so be it. At least I will not feel the annoying buzzy engine.
2) when I step in the gas, only the traction motor should propel the car up to 20mph or so. At 15 to 20 mph, the ICE can kick in. So far I have seen that the ice engagement is very smooth and virtually undetectable if the car is moving at 15 to 20 mph.
3) if the traction battery charge is insufficient to accelerate the car to 20mph or so, the ICE should stay on at a 600rpm idle when the car is at rest and propel the car when the gas is pressed. In this case the car will behave just like any othe conventional vehicle and no jolt will be felt. As I stated befor, this May cost a few mpg but the operation will be very smooth.

At present I am very gentle with the gas to get the car up to 16-20mph before pushing it harder, so that the ICE kicks in when the car is moving at a reasonable pace. The car is smooth, but people behind me get impatient. I know the traction motor has enough torque to give reasonable acceleration, I just want to delay ICE kick in for a second to smooth things out.

Can the software be changed to allow this?

chromedome

I seriously doubt it. There are so many interlinked components and computers in the LHD/HSD system that reprogramming one affects the others. Just check out the Prius power electronics, it's a lovely piece of engineering.

The engine can run on the Atkinson cycle where power and torque are reduced compared to normal engines. I think Toyota tuned the engine to be efficient as a generator (hence the need to run at 1200 rpm when idle charging) and for mid range power, so the redline is limited to less than 6000 rpm. I usually have enough charge to allow electric only driving at low speeds so the buzzy engine doesn't bother me.

Toyota's strategy seems to use the ICE for acceleration while the traction motor is used for constant low speed driving and adding mid range torque. Even in Eco mode, the engine will start with the power needle in the middle of the Eco zone. You have to really crawl along to prevent the engine from starting. This is my first hybrid so I'm still learning new things about it, but I would drive it like it was designed - use moderate acceleration with ICE power to get up to cruising speed, then lift off and coast/cruise on electric power. I've managed to get my daily commute up to 44 mpg.

On the performance side, with enough charge, you can a get a big electric kick by accelerating to the start of the Power zone. Pinning the throttle down just makes the engine roar near redline while not providing much more power. It's in the mid range where these hybrids are most fun

There's also misleading PR about new hybrids being able to run at xx mph on electric mode only. Yeah, for 10 seconds and for a few hundred feet maybe... There's not enough battery capacity to accelerate to highway speeds on battery only.

PirelliRC

Well you are basically talking about revamping the whole Toyota / Lexus hybrid system, not only can you not re program the unit itself to do what you are describing, i am willing to bet money the dealer or any mechanic wont touch it either. It'll be easier to engineer a new vehicle.

When the battery is not too low and the system has initialized itself properly from a cold start, as you come to a stop the engine shuts off and there is virtually no noise at all. Only when the battery needs to be charged or the system is cold do i get a low buzzing noise, which i hardly notice i may add. I dont know i kinda like the electric whine and hearing the regen as well, i guess im new to the hybrids so maybe that is why but it really is not intrusive at all for me. It is MUCH quieter than a regular petrol engine so i do not see the problem.

Maikerusan

No the software cannot be changed like that. Having had a Prius for a number of years, I can attest to the fact that the software is well designed. It's not just for "what happens right now as you press the gas", but it is designed for long life, maintaining the hybrid battery in optimum condition and a whole host of other features.

Believe me, Toyota/Lexus knows what they are doing with hybrids and are acknowledged as the world leader on them.

zes

I agree. But a Lexus is supposed to be smooth and quiet. A 4 cyl engine idling at 1200 rpm can never be smooth and quiet no matter how well it is damped. I am sure all of us have had 4 cyl cars that idle very quietly at 600-700rpm. It sure would be nice if they can slow it down a bit. Also the ICE engages seemlessly when the car is at 15-20mph so they could have made an effort to engage it at that speed. Sometimes there is a slight thump when the IC engages from rest. This is a Lexus after all, not a Toyota Camry Hybrid.

chromedome

If you want smooth, get a GS450h or LS600h The other Japanese and German hybrids aren't smooth either, not until you get to Panamera E-Hybrid territory.

I think Toyota chose this engine for cost and efficiency reasons. I don't think they have a small V6 that runs on the Atkinson cycle, the IS250 engine doesn't. An ES450h would be interesting but too pricey and wouldn't get anywhere near the mileage as the 300h.