Land Cruiser vs Highlander Hybrid AWD on ice

[Nuke]

We live where the roads are ice or packed snow for a good portion of the winter. Off-roading is not a criterion in regard to this question. Which vehicle, the 2024 LC, or Highlander, would be the most stable on slick highways? Both have full-time All/4WD but implemented in markedly different fashions. Of course, the LC has the Torsen center differential, which can be locked in extreme conditions such as deep snow, but this would not be our typical scenario, only ice. The Highlander has true independent power control front and rear. And of course, both vehicles employ "smart" sensing/braking independently by wheel. So, I suppose the root of my question is, which system would be "smarter" on ice as far as applying power and braking to the individual wheels, such as if the vehicle lost traction and was entering into a potential skid? Presuming Michelin X-Ice tires on both? (Yes, tires are a BIG factor!)

 

[LC-120]

Based on many years of winter driving I would recommend one thing: narrow winter tires.
LC is on off-roader. If not interested why would you need a ladder frame, a solid rear axle and a low range gear? They mean extra weight and extra money.

 

[Nuke]

I apologize for the misunderstanding. I still wish to do some off-roading, as cannot get it out of my blood, but admittedly at my age (81), the primary use will be on pavement. Yes, you are correct regarding narrow tires, having driven/commuted many miles in adverse conditions. However, not sure if on ice that narrow tires would have an advantage, but definitely in snow.

 

[LC-120]

Driving on ICE is dangerous no matter the car. If you have to do it, the tires are the main issue. Make sure you get the right ones because there are major differences even between high quality winter tires.
2022 Tyre Reviews Studless Winter Tyre Test - Tyre Reviews and Tests
Nokian is among the best if not the best. And this is what they recommend: "In the winter, narrow tires are better under extreme conditions as they provide higher surface pressure against the road. Narrow tires also work better than wider ones in loose snow and slush. Wider tires, for their part, will offer more grip on hard surfaces"

 

[Nuke]

Thanks LC-120! I am presently running Michelin X-Ice tires during the winter, and correct, they make a BIG difference! I have to smile, as also correct, wide tires are typically a detriment. The macho trucks here typically run very wide tires, and also are typically part-time 4WD, meaning at highway speeds the truck manufacturer advises against running in 4WD when any dry pavement is present. If one does, the 4WD drive system "binds", resulting in excessive wear and failures. Sure glad to see that Toyota is using a Torsen center differential in all trims of the new Land Cruiser so running in 4WD full-time and at any speed is not an issue.

 

[LC-120]

Sure. LC120 and 150 got the Torsen center differential. It means permanent 4WD. 2WD mode not possible.
Same for all Lexus GX/LX and the 4Runner V8.

Toyota says this about Torsen:
"Main advantages:
Lightweight and Compact• The output components (IG, SG) overlap by their difference in diameter, making for a compact design.• High torque distribution ratio is possible with just a single planetary gear mechanism.• The structure combines the differential function and
the limited slip function in the same hardware.
Excellent strength and durability.• The design can be upgraded relatively easily, by increasing the number of Planet Gears.
Low cost.• The Torsen structure is simple and easy to process. The system does not require any actuators or electronic control units."

 

[Wanderlost]

I think the most notable difference will be in duty cycles. While the parking lot performance may be similar, there are many reports of overheating the latest unibody all-wheel drive systems.

 

[Nuke]

I think the most notable difference will be in duty cycles. While the parking lot performance may be similar, there are many reports of overheating the latest unibody all-wheel drive systems.

With "unibody all-wheel drive systems" are you referring to that is which is in the Highlander hybrid and others, i.e. no mechanical connection between the front and rear axles, but utilizing electric motors? Or, the "dynamic torque-vectoring" system on the non-hybrid unibody vehicles? The traditional driveshaft-driven system on body-on-frame vehicles with a center Torsen are tried and true. I have noticed the rear drive system on the Crown is water-cooled, so that must generate a good deal of heat.

 

[Wanderlost]

With "unibody all-wheel drive systems" are you referring to that is which is in the Highlander hybrid and others, i.e. no mechanical connection between the front and rear axles, but utilizing electric motors? Or, the "dynamic torque-vectoring" system on the non-hybrid unibody vehicles? The traditional driveshaft-driven system on body-on-frame vehicles with a center Torsen are tried and true. I have noticed the rear drive system on the Crown is water-cooled, so that must generate a good deal of heat.

Affirmative, including the latest torque-vectoring systems from Toyota, Honda, and Ford. Unibody torque-vectoring all-wheel drive systems offer better performance over short durations compared to brake-vectoring systems but are not suitable for extended use because of the heat generated.

 

[LC-120]

Could you please clarify what do you mean by "unibody all-wheel drive systems"? I still do not understand. The question was A or B and the answer was "affirmative".

 

[Wanderlost]

Could you please clarify what do you mean by "unibody all-wheel drive systems"? I still do not understand. The question was A or B and the answer was "affirmative".

I don’t have any experience with unibody all-wheel drive systems, so my observations are based on anecdotal reporting. Deductively comparing body-on-frame with unibody all-wheel drive systems, it seems reasonable heat will build up faster over time in unibodies. Thermal stress may be concentrated in the transmission or rear differential depending on unibody architecture, however I would expect body-on-frame systems to generate less heat over time.

 

[LC-120]

There are two tipes of SUVs. The tougher Body-on-Frame and the Unibody. The all wheel drive system is a different story. There are Body-On-Frame SUVs with very basic AWD systems and Unidody SUVs with a very performant AWD system.
Please refer to a specific system/SUV regarding the thermal stress.

 

[Nuke]

There are two tipes of SUVs. The tougher Body-on-Frame and the Unibody. The all wheel drive system is a different story. There are Body-On-Frame SUVs with very basic AWD systems and Unidody SUVs with a very performant AWD system.
Please refer to a specific system/SUV regarding the thermal stress.

As specified, yes, the two vehicles do have markedly different systems, and yes, the LC employs a body-on-frame system, and the Highlander, in particular the hybrid as the question is directed to, is an AWD system on a unibody. In the Toyota hybrid there is no rear driveshaft, but an electric motor. However, I would not term either "basic", as both are "smart", utilizing individual wheel rotation sensors, etc., etc. I am not too concerned regarding the thermal stress. In fact, that had not even crossed my mind. The scenario, one is driving on a very slick iced-over highway. Which will retain stability the best, given both are running, say, Michelin X-Ice tires?, Which is the "smartest" on ice, figuring out where to apply power or braking to keep the vehicle safe? My guess would be the system on the hybrid, as it selectively apply power to the front/rear independently, in addition to braking. A caveat is the scenario is an iced-over highway, not deep snow, as the LC would obviously be superior.

 

[LC-120]

Looks like a lot of AWD systems in Toyota cars today.....

Probably different ones for 4Runner, Landcruiser, Sequoia, Tacoma, Tundra. Wow!

 

[Nuke]

Great information! Of the systems described, Torque-Vectoring sounds like possibly the best, however, the magnetic clutch makes me a bit nervous. The system on our Highlander Hybrid works great, and no clutches, i.e. one less failure point. Sure wish he would have described and compared the system on the Land Cruiser. Possibly I am incorrect, but they all, even the LC, are able to direct power to the wheels which need it the most, even if only by selective individual wheel braking. Brings back memories, getting out of the vehicle to lock the hubs, high/low range, etc. Of course, the LC has high/low range, a transfer case, but with the added benefit of selective braking and the Torsen lockable center differential. Put a winch on front and nearly unstoppable! I'm talking myself into one! Or, maybe the GX Overtrail, as it has KDSS front/rear sway bar disconnects, but only the front for the LC. What am I thinking of at 82? "Back in the days"