[mojo]

It will be interesting to see how the 300h's E-Four Wheel Drive compares to the 200t's mechanical based system.

Called E-Four, the system uses an additional electric motor to drive the rear axle, providing more grip and better vehicle control on slippery surfaces. The front axle is propelled by power from the hybrid petrol engine or electric motor, or both in combination.

E-Four works intelligently, varying the amount of drive torque to the rear wheels in line with driving dynamics and road conditions, to secure just the right level of stability when pulling away or accelerating in low-grip conditions. As operation is automatic, the driver doesn’t have to think about engaging AWD.

http://blog.lexus.co.uk/2014/09/new...rip-with-e-four-all-wheel-drive/#.VBh6AfnRPVI

 

[FSport]

Also looking forward to what this system is like and how different it is than the 200.
Some journalist should consider doing a comparison of the both of them.

 

[mister]

Should be a fun thing to get to know during a test drive. I do wonder how much you will feel it though, unless you have to do some more intense driving, like snow or swerving etc...

 

[Thai]

At least in theory, this system is not for HD usage.

Battery/electric powered rear wheels will have limitations in terms of duration. So, lets say that you are going to work and find that your 300h is buried under a lot of snow. Will there be enough juice and quantity of battery/electric power to rock your 300h back and forth for a period of time to break free?

The other issue (in theory) is performance...since most power is still at front axle, 300h can never achieve equal bias or rear bias push that is needed in a sports car around a corner to reduce understeer. I believe that this is where the 200t AWD system is sportier since it can deliver up to 50% of power to the rear.

BTW, this system is already in the RX300h. From reading the Lexus forums, the RX hybrid does well in snowy conditions.

 

[mister]

I imagine with the extra torque that an electric engine gives that most hybrids are good in the snow.

 

[Thai]

I imagine with the extra torque that an electric engine gives that most hybrids are good in the snow.

but for how long? If you're stuck in a ditch and trying to rock yourself out, then will it gives sustained power to the rear wheels long enough?

I don't have the answer...but just wondering.

 

[mojo]

but for how long? If you're stuck in a ditch and trying to rock yourself out, then will it gives sustained power to the rear wheels long enough?

I don't have the answer...but just wondering.

Well that is the beauty of hybrid vs pure EV, the situation is not as dire IMO. The flip side is will the extra torque deployed from 0 help or hinder the efforts to get unstuck?

 

[Thai]

Well that is the beauty of hybrid vs pure EV, the situation is not as dire IMO. The flip side is will the extra torque deployed from 0 help or hinder the efforts to get unstuck?

I guess that it depends on how much pressure is applied to the gas pedal by the driver. The torque supplied by the electric motor depends on how deep you press the gas pedal.

 

[mister]

How would the extra torque hinder efforts to get unstuck?

The flip side is will the extra torque deployed from 0 help or hinder the efforts to get unstuck?

 

[Thai]

How would the extra torque hinder efforts to get unstuck?

I "assume" that he meant max torque all at once may actually cause more slippage than traction???

Anyway, the battery powering the rear wheels will act like a gas engine...torque is applied depending on how you press the gas pedal.

 

[avocado]

I think that Traction Control limits slippage but I forget how it does it. I thought it starts off in 2nd gear, but am not entirely certain.

 

[Thai]

I think that Traction Control limits slippage but I forget how it does it. I thought it starts off in 2nd gear, but am not entirely certain.

Usually only if you select SNOW mode does a car start off in 2nd gear. Traction control works at the axle level...it does not change transmission gears. TC compares wheel speed difference b/w two wheels on the SAME axle...it brakes the one that is spinning the fastest (to even out the speed on both wheels), which it presumes is the one that is slipping.