2018 Lexus LS Official Thread

Nice link and read .

Does this indicate your intention to get the LS you've always wanted?

May make a nice anniversary or birthday gift.

 

I poo-poo the trend away from the HSD and back into conventional transmissions. I don't want another part to potentially fail and I don't want shifting. I want all the power all the time with smoothness, even at the cost of HP.

The LS600h was an excellent vehicle with the planetary gears. Why are they ruining this?!?!?!?!

Keeping in mind one of the only reasons I don't have a Porsche plug-in hybrid right now is because of the conventional transmission. Awesome car with shifts means no sale. If I want aggressive shifting, I'll drive an exotic. If I am lumbering around town, I want a car that lumbers too.

 

I'm pretty positive the 4 speed part of the Multi-Stage Hybrid is just planetary gears. Most step automatics make use of them.

This system might have come out of the partnership with Ford on a hybrid truck.

 

It's a typical HSD with a 4-speed auto bolted onto the output side of the HSD. Car and Driver had a good comparison to a semi-truck transmission.

Both the LS and LC hybrids get this thing:



Not only is it a full conventional transmission but also a full HSD system with extra bits to bolt it together. One of the benefits is that you can now get EV only mode into higher speeds like over 80mph. But the downside is shifting. Because the tranny is on the output side of the HSD there will be shifting. And they try to spin this as a positive, making it feel less like a rubber band and more like a conventional car...

Welcome back transmission flush maintenance, torque converter lag, and gears eventually wearing out meaning a rebuild or replacement. All things you never need to worry about with a standard HSD.

I see lots of downsides. I don't want any of my new vehicles having a transmission. We've owned lots of Lexus products, and if they make the RX or NX next gen have this crap, we jump ship. Just like they refused to make a pure EV for so long had to jump to Nissan for a Leaf.

Link to C&D: Details of the New Lexus Multi Stage Hybrid – Feature – Car and Driver | Car and Driver Blog

 

Yes, and modern step automatic transmissions use planetary gears. A cut away photo was posted when the first Lexus with this was released.

Current step autos have maintenance intervals in the range of 100k miles; maybe as low as 50k miles. Gen2 Prius owners were draining the transaxle just as often because the HSD cooks the automatic transmission fluid in it. We didn't see a fix for that until gen4.

Without a torque converter, there can't be torque converter lag.

The average age for registered personnel cars in the US is over a 11 years. Something like 90% of cars sold here are an automatic of some sort. Transmission reliability has come a long way, and Toyota has been building some pretty solid ones for awhile now.

 

While they use planetary gears, they aren't staticly geared (obviously as that defeats the purpose) so there will be shifting.

Even the exotics with dual clutches and rev matchers so that the shifts are seamless and quicker than a human, still produce a jiggle. And it is easy to fake those out because it has to anticipate your next gear but has no knowledge or the road/traffic.

I guess I will go take a test drive of one when they come out. But I was sorely disappointed with the Panamera 4-E Hybrid because of the transmission. If it felt like a Tesla, or any of our Prii, or the Lexus RX 450h, sold. But it felt like the early 2000's Honda Civic Hyrbid with a transmission. It is really hard to go back to shifts. It irritates me every time I am in a rental car (6-10 days a month) that isn't a hybrid. No way I am owning that.

 

For me, shift points or not doesn't make a difference. I adapt to the car.

Companies are already developing 2 and 3 speed transmissions for electric cars.

 

I'll go ahead and link this video, with the note that the fake 10-speed mode is apparently only active in Sport+ or M modes:

So, ultimately, the Toyota hybrid system has three main problems.

First is the compromise in MG2 performance - if you gear short for efficiency (reduced current) at low speeds, you run into RPM limits at relatively low vehicle speeds. In a lighter vehicle, and/or one with modest performance goals, this isn't much of a problem - power demand at low speeds isn't incredibly high, so the gearing can be decent for higher speeds - the Gen 4 Prius, as an example, tops out at 116 MPH (187 km/h), IIRC, which is plenty for that car.

However, heavier vehicles demand more power at low RPM, and therefore shorter gearing - as another example, the Prius Prime tops out at about 99 MPH (160 km/h). You could also make a bigger motor to get that current-handling capability at low RPM, which is why the larger vehicles use the P310 family (or now, for the Camry, the P710), but that hurts weight, cost, and efficiency. (They also do it to get more power overall, though, so it makes sense.)

Way back with the L110, though, the original GS 450h gearbox (used in L110F form in the LS 600h), Toyota had another solution to that problem - why not put a 2-speed reduction box on the MG2? That way, the same MG2 could be geared for both good acceleration and efficiency at low speed, as well as capability of high speed.

Here's an acceleration video showing an L110F-equipped LS 600h twice, once at full throttle to near top speed, and once where the vehicle was rolled onto the throttle at higher speed. During the first run, there is a noticeable, albeit slight, momentary reduction in engine power, at around 125 km/h (77.7 MPH) indicated. During the second run, I have to assume the throttle wasn't applied fully, as the shift occurs at 100 km/h (62.1 MPH) instead. Note that the power split device's path to the wheels doesn't shift, so this shift was likely to reduce power going through MG2 momentarily to make the shift more smoothly:

Now, this addresses the MG2 compromise problem (to an extent anyway - 2 gear ratios still means that there's some compromise)... but there's another problem with the Toyota hybrid system, and that's MG1's RPM range. See, as the first video hints at, MG1's rev limit actually sets an upper bound on engine RPM for a given vehicle speed. For an economy car or a cruiser, that's OK. For something that intends to be higher performance (like the LC 500h), or something that wants to do more with less engine (LS 500h), you need to get to higher engine RPMs faster.

So, the same compromise as before appears, in a different form - gear short, and the vehicle won't be able to shut off the engine at much speed at all (the other side of MG1's rev limit), and it'll have an increasing minimum engine RPM as speed increases hurting high speed efficiency. Gear tall, and MG1 can't get the engine up to full power until very high speeds. The Gen 4 Prius can't reach full power until about 88 MPH as a result of being geared fairly tall, and the first video talks about a L110-based powertrain (I think it's the GS 450h's, based on the 6000 RPM limit) being unable to reach full power until about 120 km/h (74.6 MPH).

The third problem is somewhat related to both of these problems, too - when you're at the extremes of the power split device's range, high powers are going through the electrical path, reducing its efficiency. At low speeds, especially with tall gearing, very high currents are going through it, making heat a real issue, especially with heavy loads (because that means sustained high currents) - note that Toyota hybrids tend to have low or nonexistent tow limits, when their ICE competition tends to have much higher tow limits (especially in the European market). And, note that we've never seen a Toyota hybrid truck to date. (GM's hybrid truck transmission was a compound split design, that offered multiple fixed gear configurations that avoided power split behavior, in addition to the input split and compound split modes (which themselves improved high load power handling capability). During towing, those fixed ratios were greatly preferred, because they meant that the electric motors didn't have to handle a high percentage of engine power.)

So, this transmission is meant to solve all three of those problems. Because it offers four ranges of operation, a low range that gets engine power up quickly is available, and allows efficiently getting a heavy load moving (or getting a lighter load moving quickly). Then, it can shift through higher ranges to optimize efficiency and minimize power flowing through the electrical path as speed increases.

Now, it is likely that some shifting behavior will be perceptible, especially depending on how much Toyota's designed this to back off during a shift to save the bands and clutches. However, if they don't have to back off too much (and closer ratios than the L110's gearing may help, although now all power is going through the reduction device, rather than only MG2 power), the power split device can use its CVT-like behavior to mask the shifts.

Also, note that I talked about trucks and towing capacity. This thing is really a bit excessive for the LS or the LC, and I'd expect two or three gears for that application. But, trucks need more ratio choices to optimize efficiency and minimize engine power going through the electrical path... and Toyota has patents on truck applications of a hybrid transmission with a power split device feeding a 4-speed planetary-geared transmissions. And, why design multiple high-power RWD hybrid transmissions? The patents aren't showing the exact layout of the L310, but my prediction is that we'll see the L310 in the Tundra before too long.

 

My new dream machine is the LC500.

While getting the wife's RX450H, they had one in the show room.

Sat in it and now I have a new pining . Although I dont golf, so I won't use the trunk for what is designed for.

Would make an excellent mid life crisis car, but will require many pennies to be saved.

 

I agree on the Multi Stage system being intended for a truck. Ford and Toyota had a partnership on developing a hybrid truck, but that split up without any announced progress or product. It appears they disagreed on what hybrid layout to pursue. Toyota wanted to stick with their power-split expertise, and Ford is opting for a parallel hybrid.

The Tundra and F150 have a design cycle roughly synced up. There is some early news of a 2020 hybrid F150. I'd expect a hybrid Tundra around the same time.

 

"the Prius Prime tops out at about 99 MPH". I've had mine over 110 MPH. I know, you'll say Toyota Prime has another problem, Speedometer Error!!
I don't know where you got your numbers, but mine was on the northbound 5 Fwy to Bakersfield, on level road. Oh and in that trip only averaged 62mpg

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Mine are from reported gear ratios and MG2 rev limit, although maybe the reported gear ratios are wrong, at least for the US market, in that case.

 

A coworker has an ES300h and it is a quiet, smooth ride.

If I got one though, I would be Prius-less and would then have hang out at Club Lexus .

 

And that would be completely unacceptable!!

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I agree completely .

The typical response over there to an issue is: did you take it to the dealer.

I would miss the good questions and mental stimulation .

 

{makes sure Sonic parked out of site}
And good riddance!