Hybrid electric AWD

[svtrit]

Does anyone know if electric AWD acts like a locking rear or “posi” ensuring both wheels try to move the car equally? I’m buying my first hybrid and was thinking about that today. It’s a 25 Toyota Sienna.

Or, if one wheel is needing more energy to move and the other spins freely, will the power go to that wheel? It seems electric rear drive is a perfect set up for being stuck and getting out.

Thanks.

 

[ctechbob]

Would all depend on how they set it up. If they have a regular ol open diff between the motor and the wheels, then no. If they have it set up with some clutches to do torque vectoring, or a limited slip diff, then sure. Alternately they could use one motor per wheel for complete control.

Not familiar with what Toyota uses, but I'm sure the info is out there somewhere.

On another note, I went looking for the info, found this.

Holy crap that's cheap. If it is indeed the motor and the diff, then that seems like a steal.

 

[SC Maintenance]

Which hybrid?

For example Toyota Hybrid AWD Rav4, and others I believe, simply have a electric motor on the front diff and a second electric motor on the rear diff. Both diff's are open but do use ABS to limit wheel slip. But definitely not posi like.

Now Rivian "quad motor" option puts a single motor driving each wheel seperately - so in that configuration in theory they could put exactly as much torque as each wheel could handle without slip. However its EV not hybrid.

So - which car?

 

[DirectRejection]

Alrhough similar otherwise, my 2019 Lexus UX 250h F-Sport had a significantly more sophisticated power distribution system than my current 2024 Corolla Cross Hybrid.

Your Sienna is not gonna have much that is fancy.

 

[We're Metals]

I drive my Rav4h across construction sites daily. Very minimal wheel slip in the rear. Front is definitely an open diff. Not sure how it would behave in snow. As long as it has ground clearance, it is very capable in the dirt.

 

[ATex7239]

 

[svtrit]

Thanks for the info. I was assuming one motor per rear wheel, but it seems that is not the case.

She will enjoy the AWD. Our Town and Country really likes to spin the front wheels (even under careful driving).

 

[andrew_j]

It all depends on much effort Toyota put into programming it all. It can range from terrible to amazing .

 

[meep]

The typical ones dont “lock” front rear RPM. One can spin while the other does not. We have a rav4H and it is AWD. It is delightfully programmed but if you watch the torque output display it appears that the rear end is only really used during torque transitions - it’s a “kicker” motor. Now, if you kick it off the line it is more than a willing partner and can repeatedly scratch off the rear wheels, but it’s not sustaining output - just helps get you going. It’s not balancing output from the front.

I don’t know what it does during an active front wheelspin. I presume it would goose the rear motor until rpm’s balance.

 

[edyvw]

Thanks for the info. I was assuming one motor per rear wheel, but it seems that is not the case.

She will enjoy the AWD. Our Town and Country really likes to spin the front wheels (even under careful driving).

It is ok set up for around town. But not as good as mechanical AWD.

 

[t1snwrbrdr12]

With these Toyota type AWD hybrids, only electric powers the rear wheels correct? So would you be able to replace tires in pairs, as the front and rears aren’t mechanically linked? No transfer case / center diff to wear out by spinning at drastically different rates…just curious.

 

[dogememe]

Many toyota eAWD hybrids or whatever they call it are front wheel drive vehicles with a small electric motor in the rear that can apply a limited amount of power to the rear wheels. Both front and rear are open diffs and since there is no mechanical connection between front and rear they use creative traction control via brakes to reduce wheel slip.

There's nothing wrong with that approach... it's cost effective, easy to package, and very efficient. Just, not what most people think of when they think of AWD/4WD.

 

[svtrit]

With these Toyota type AWD hybrids, only electric powers the rear wheels correct? So would you be able to replace tires in pairs, as the front and rears aren’t mechanically linked? No transfer case / center diff to wear out by spinning at drastically different rates…just curious.

That is a really good question....

 

[Cujet]

There are some YouTube tests that show exactly how well the AWD systems work on various vehicles. They typically use rollers to disable a wheel or three. Then mash the gas to see if the vehicle can motivate itself off of the rollers. Some can't.

Even so, all of these AWD setups will provide some advantage over an open differential FWD setup by driving at least one rear wheel. And you will find that owners of the vehicles that have underperforming AWD systems still have good results in modest conditions.

While I live in FL and don't care about snow traction, I've found these videos fascinating and have spent way too much time watching them. As the differences between makes and models are significant.

 

[andrew_j]

There are some YouTube tests that show exactly how well the AWD systems work on various vehicles. They typically use rollers to disable a wheel or three. Then mash the gas to see if the vehicle can motivate itself off of the rollers. Some can't.

Even so, all of these AWD setups will provide some advantage over an open differential FWD setup by driving at least one rear wheel. And you will find that owners of the vehicles that have underperforming AWD systems still have good results in modest conditions.

While I live in FL and don't care about snow traction, I've found these videos fascinating and have spent way too much time watching them. As the differences between makes and models are significant.

I can test the AWD on the daily after storm if I want leaving my driveway planting front tires on ice and one or two on slippery surface on rear. AWD is so all over the place, the best I have experienced has been Subaru pure mechanical with LSD. Also Acura SH-AWD is great which migrated into Honda AWD for recent Pilot/Passport/Ridgeline. The 13 Acura RDX I have seems to have FWD+ and is abysmal and worst owned.

The 18 Tiguan 4motion is actually really good with a haldex diff on rear.