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The 2019 Toyota Prius Is Likely Getting All-Wheel Drive

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Old 12-03-18, 07:39 AM
  #31  
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Originally Posted by 4TehNguyen
that is not a real AWD system, just some quasi AWD
Its better than no AWD system. Its a Prius, it doesn't need a "real AWD system".
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Old 12-03-18, 10:02 AM
  #32  
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Originally Posted by 4TehNguyen
that is not a real AWD system, just some quasi AWD
It is a modern AWD system and it is the evolution of electronically controlled AWD systems.

An AWD system has come to represent a drivetrain device that automatically (with no input required from the driver) switches from driving only 2 of the wheels to driving all 4 wheels.

The first AWD systems were mechanical. That evolved to electronic control. The similarity was that both controlled a central mechanical differential coupling in the other axle to the powertrain.

Toyota's eAWD is a further evolution of electronically controlled AWD. If you have electronic control and you have electric drive, why do you need a mechanical connection between the 2 axles? Why not make the coupling electronic also? That allows for much greater, independent control of 2 axles; the torque available to the 2nd axle is no longer dependent upon the torque available to the primary axle, so that each axle can theoretically have as much or as little torque as wanted.

Originally Posted by situman
The rear motors only has 7hp. I'm not sure but something tells me the extra rear motors is just dead weight. Although lawn mowers can be quite scary even with just 1hp.
It is not the power that matters; it is the available torque that matters since the rear axle is not the primary driving axle in the Prius. And the great feature of electric motors is that maximum torque is available from very low rpm.
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Old 12-03-18, 12:08 PM
  #33  
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rear motor is just an assist motor like the Rams etorque at low speeds, article said it doesnt even operate above 43 mph. Its pretty much an assist axle not a drive axle. Thats why its a quasi AWD
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Old 12-03-18, 01:29 PM
  #34  
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Originally Posted by 4TehNguyen
rear motor is just an assist motor like the Rams etorque at low speeds, article said it doesnt even operate above 43 mph. Its pretty much an assist axle not a drive axle. Thats why its a quasi AWD
The problem is in how HSD works the engine must spin up to provide power to the rear motor. So if you're stuck then the front wheels have to spin way more than needed, either that or the traction control completely takes over and you don't move at all. Older AWD Toyota hybrids have this problem and you can't turn off traction control. If Toyota wasn't so stubborn they would put in a much larger battery pack and this problem would be greatly reduced or eliminated.
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Old 12-03-18, 03:52 PM
  #35  
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Originally Posted by Lexus2000
The problem is in how HSD works the engine must spin up to provide power to the rear motor. So if you're stuck then the front wheels have to spin way more than needed, either that or the traction control completely takes over and you don't move at all. Older AWD Toyota hybrids have this problem and you can't turn off traction control. If Toyota wasn't so stubborn they would put in a much larger battery pack and this problem would be greatly reduced or eliminated.
this system is supposedly much improved from before... we already had some tests with UX250h, it works fine for its intended purposes.
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Old 12-03-18, 03:53 PM
  #36  
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Originally Posted by 4TehNguyen
rear motor is just an assist motor like the Rams etorque at low speeds, article said it doesnt even operate above 43 mph. Its pretty much an assist axle not a drive axle. Thats why its a quasi AWD
why would it operate over 43mph? And what does it have to do with mild hybrid system? Point of this system is to take you up icded or snowed incline, where FWD cant move anymore... it is not supposed to be a rally car.
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Old 12-03-18, 06:38 PM
  #37  
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Thank you to Toyota for toning down the design language on the car. Definitely looks nicer, IMO.
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Old 12-04-18, 10:06 AM
  #38  
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Originally Posted by ABC
Thank you to Toyota for toning down the design language on the car. Definitely looks nicer, IMO.
I wonder what is the future for Prius Hybrid... I see Prius PHEV, Prius EV but what is the point of hybrid 2-3 years from now? New Corolla sedan is now same wheelbase, same engine, same rear suspension and nice interior. This is what Prius always had before - it was slightly larger, independent rear suspension, it had hybrid > 50 MPG, it had different looks and new interior tech (smart entry, self parking, larger screens).

Now Corolla has everything, you can get it even with HUD. So in the future, they will still have to distinguish Prius with crazy looks, and advanced tech such as large screens (current one has 11.6" optional). Just do a better job with exterior than in 2015.
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Old 12-04-18, 11:09 AM
  #39  
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Originally Posted by spwolf
this system is supposedly much improved from before... we already had some tests with UX250h, it works fine for its intended purposes.
Still nowhere near up to the abilities of a mechanical system or in a BEV like Tesla. Which is disappointing you'd think with an electric motor in the back it would be easy to modulate power and control wheel slip via ABS but because the hybrid battery has such a low capacity the engine must rev up to generate power. Which results in needless front wheel spin or if the front wheels have good traction then the rear motor becomes useless.

To be clear I am talking about a scenario where the vehicle is stuck or moving very slowly. In other conditions the rear motor is effective.
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Old 12-05-18, 06:52 AM
  #40  
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Originally Posted by Sulu
It is not the power that matters; it is the available torque that matters since the rear axle is not the primary driving axle in the Prius. And the great feature of electric motors is that maximum torque is available from very low rpm.
And how much torque does a 7hp motor has? If it the front has low to no traction, will the rear motors have enough torque to move a 3400 lb vehicle out of the way? I have a feeling it is highly unlikely.
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Old 12-05-18, 06:54 AM
  #41  
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Originally Posted by spwolf
why would it operate over 43mph? And what does it have to do with mild hybrid system? Point of this system is to take you up icded or snowed incline, where FWD cant move anymore... it is not supposed to be a rally car.
I highly doubt such a weak motor can be helpful on an incline of any sorts. Maybe if the Prius weighs as much as a small scooter.
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Old 12-05-18, 12:27 PM
  #42  
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Originally Posted by situman
And how much torque does a 7hp motor has? If it the front has low to no traction, will the rear motors have enough torque to move a 3400 lb vehicle out of the way? I have a feeling it is highly unlikely.
Since horsepower is dependent upon torque and motor rpm, even if torque is high but rpm is very low (which is the case with electric motors), horsepower will be low.
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Old 12-12-18, 12:07 PM
  #43  
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Default 2019 Toyota Prius AWD-e First Drive Review



KOHLER, Wis. — Depending on where you live, the unavailability of all-wheel drive on any certain car model could be a deal-breaker. Whether they need it or not, some people refuse to go without, even if they're not concerned enough to switch to snow tires when they set their clocks back an hour in the fall. Having four driven wheels won't make you stop any quicker on ice, but the "AWD" badge on the back instantly adds 15 confidencepower. If the lack of all-wheel drive has been what's kept you from enjoying the impressive efficiency of a Prius hybrid, Toyota has something new it'd like to show you.

Toyota unveiled the 2019 Prius AWD-e at the 2018 Los Angeles Auto Show. With 50 miles per gallon combined, it'll be the most efficient all-wheel-drive vehicle you can buy without a plug when it goes on sale in January 2019. For those who swear by high mpg but want AWD (or vice versa) this is a great thing. The Prius nameplate has been a go-to for those who want a car that's economical both up front and at the pump. Now, those four-wheels-driven stalwarts in the Snow Belt can enjoy similar frugality.

Not only that, but Toyota has listened to the masses and scaled back the visual weirdness for 2019. The updated lighting front and rear makes this car much more approachable. Inside, gone is the sea of white plastic, which simultaneously managed to look both dramatic and cheap. Instead is more palatable piano black plastic on the center console, the shifter surround and the steering wheel. There have been a couple other minute tweaks, such as placing seat heater buttons in better view near the cupholders, and adding extensions to the sun visors. Finally, the Prius adopts the grade naming of the rest of the Toyota lineup – L, LE, XLE and Limited — with the AWD-e version available in LE ($27,300) and XLE ($29,740) trims.

Power to the front wheels comes from the same 1.8-liter gasoline-fueled four-cylinder engine as every other Prius, along with a pair of motor/generators, to provide a combined 121 horsepower. Unlike other Prius models that use a lithium-ion battery pack, the AWD-e instead relies on a nickel-metal hydride pack. Toyota says the battery chemistry switch was made in order to provide superior cold-weather performance.

The all-wheel-drive system in this Prius has been engineered to maintain the efficiency customers demand while providing a traction benefit when needed. As such, the rear motor — which supplies just 7.1 horsepower, but a much more significant 40.6 pound-feet of torque — operates independently from the rest of the powertrain. There's no driveshaft to link the rear axle to the gas engine or front motors. It puts equal power to each rear wheel through an open differential with no mechanical torque vectoring involved, and the wheels can be braked independently as needed to compensate.

The rear motor isn't providing power all the time, either. It's always on from 0 to 6 miles per hour, helping to pull away from a stop or through a corner with maximum traction (it works in reverse as well). From 7 to 43 miles per hour, it only engages when needed. It'll also power up in situations where you could potentially lose grip, calculating yaw and speed — say, under hard cornering — to prevent understeer and help keep you on your line. Otherwise the rear motor stays quiet to conserve energy, and the magnet-less design of the motor means it doesn't add resistance when not providing power. That also means that this motor isn't used for regeneration; the front motors handle that.

Above 43 miles per hour, the rear motor doesn't activate at all. Toyota says this is not a limitation of the system, but instead a feature or choice in order to provide the efficiency and fuel economy
figures Prius buyers demand. As deputy chief engineer of the Prius, Shoichi Kaneko, told us, customers on the colder, snowier Japanese island of Hokkaido were primarily concerned with traction at low speeds, where it could mean holding up a line of drivers behind you at a stop. At highways speeds, the car relies on the same tech as the FWD Prius to provide stability.

"For Prius, obviously, fuel economy is always top of mind," Kaneko-san said through a translator. "And in addition, we've had this secondary target where we want to go expand our base for our environmentally friendly vehicles. Based on that, we wanted to create a four-wheel-drive system for the Prius that didn't sacrifice fuel economy, but that would be a relatively inexpensive system that would allow us to sell Prius to new people."

For our drive, we started by taking the Prius AWD-e out on public roads in and around Kohler. It was cold out — about 25 degrees — but it hadn't had any snow recently in the area, so our roads were clear and dry. In these normal conditions, the car feels just like a normal Prius. Apart from the few cosmetic changes inside the AWD-e, we could have easily convinced ourselves we were driving the front-drive version. Only when accelerating hard from a stop did it become at all apparent that the rear wheels were being driven along with the front. You wouldn't notice the tiny bit of bite and shove if you weren't specifically looking for it. It's a lack of hesitation that is only apparent in comparison to the standard Prius.

Otherwise, in these conditions, it's the usual Prius experience: an efficient, affordable way to comfortably get from point A to point B. It's not a quick car by any stretch of the imagination, and that's clearly not the point. Prius customers aren't looking for speed. They're looking for efficiency, and the AWD-e still has it. It offers 52 mpg city, 48 highway, and 50 combined. Compared to the FWD version, it suffers a hit of just 2 mpg across the board.

The Prius AWD-e still has Normal, Eco and Power modes to cater the accelerator response to your needs or whims. It also retains the same shifter layout, with a "B" setting that allows for a stronger regenerative braking feel, allowing you to get on the brake pedal later and less often. While we thought we'd appreciate the more direct acceleration feel of Sport mode, more power means more sound from the gas engine up front. After using Sport for a bit, we dubbed it "Groan" mode, and switched out of it. Eco mode, while providing greater efficiency, also makes it easier to drive the Prius quietly, which makes the entire car — and any electrified vehicle, really — feel more refined.

With Mother Nature — and the area's flat geography — failing to cooperate for our test, we took the Prius to a closed circuit where we could simulate the sorts of situations where all-wheel drive could prove more useful. With the help of some snow-making machines and a front end loader, we had a small circuit that turned from asphalt to dirt to gravel to snow, including a hill of snow near the start. We had both FWD and AWD Priuses on hand for testing, each wearing its stock set of all-season, low-rolling-resistance tires on 15-inch wheels.

While we weren't allowed to take the FWD Prius over the hill, we had the chance to take it around the rest of the track a number of times. With a little bit of effort, we could get the Prius to understeer a smidge on the loose surfaces. With enough gusto, we could overcome the nannies and get it to plow more aggressively while cornering through the snow, though it resisted the urge better than we had expected.

In the AWD-e, we headed for the snow hill first. We stopped completely on the icy incline. After a moment, we put our foot into the throttle. The Prius paused a half beat, then slowly pulled up and away. It built speed slowly with smoothness and linearity as it climbed, and kept its nose pointed straight as it crested the small but steep hill. We repeated this exercise multiple times that day, and each time was the same: steady, smooth and undramatic.

We flogged the poor little Prius harder with every lap of the course. Each uneventful pass through the snow slalom had us taking it a little faster through the slippery curves. On many of the laps, a brave man waited on the outside of a curve with a snowblower to replace the white stuff we displaced as we passed. We could hear the quiet, muffled clicking as the stability control worked its magic, but weren't able to push the Prius AWD-e into understeer — the higher cornering speeds it allowed over the standard model meant crossing that threshold could've potentially meant a bad day for snowblower guy. Or perhaps not at all, depending on how well the car could recover. We weren't willing to find out; we'll save that test for an empty parking lot.

And that's was when the Prius AWD-e really began to make more sense to us, despite our affinity for snow tires. With all-wheel drive, the car mostly felt the same as any other Prius. It wasn't adding any huge, tangible change in driving behavior. What it does is subtle and demonstrates itself as a lack of the negatives you'd otherwise notice: slip, instability, hesitation, understeer. That adds up to confidence. And it's confidence you can appreciate without having to sacrifice much in fuel economy.

The majority of drivers never make the switch to snow tires in the winter, whether because of its added cost, a matter of storage space or an issue of fuel economy. Many of them would rather just have all-wheel drive. For them, there's now a Prius option.
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Old 12-13-18, 10:14 AM
  #44  
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Unless I'm missing something, the ICE doesn't need to "spin up" in order to provide power to the rear motor. The computer can pull plenty of power out of the traction battery as needed. And no, that traction battery can't drive the car for 30-odd miles like the Volt, but that's not the idea here. It's to temporarily fill in when the ICE would otherwise be operating inefficiently, i.e. with high manifold vacuum (idle, decelerating, very low speed motion). It's remarkable to me that just filling in during those conditions makes an enormous difference in overall fuel consumption, but then keep in mind that an ICE under high manifold conditions is basically just a giant vacuum pump, and such a device needs a lot of energy to keep turning. A comparably-sized diesel engine at idle just barely sips fuel by comparison--no throttle plate, so no manifold vacuum.

Based on the above article, the AWD Prius, while not full-time mechanical AWD like the successful Subaru, nonetheless does a satisfactory job of moving the car under slippery conditions. And I think Toyota engineers once again showed pragmatism in the design of this powertrain.
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Old 12-13-18, 02:13 PM
  #45  
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I've watched some videos on it, makes perfect sense for the Prius the way the system is designed.
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