A few questions….comments appreciated

[Lord Voltermore]

 The extra engine braking (and extra charging) in B mode comes from increasing the strength of the electromagnets in the charging system. The engine braking effect is caused by drag from magnetic force.The car is being slowed  by powerful magnets!

 Its not likely to cause much, if any, extra wear and tear.   
 
 When the HV battery is full the electromagnets need to be switched off to prevent overcharging.   I think the I,C,E engine takes over the engine braking by compression like a conventional car. You are being slowed by compressed air. (maybe a bit less than normal as the Atkinson cycle has a shorter compression stroke than an Otto cycle engine )

[Neil Ives]

What; you haven't read and memorised all 681 pages of the online Owners Manual?!   

[Kremmen]

I've skipped through the manuals a few times and I often spot something I wasn't aware of before.

As I understand more about the tech I can skip through various pages and concentrate more on others.

I don't need to scrutinise the fitting a baby seat pages any more, that was decades ago.

[Bazzzer]

I don't need to scrutinise the fitting a baby seat pages any more, that was decades ago.

We just put the carrycot on the floor behind the front seat.

[nowster]

The extra engine braking (and extra charging) in B mode comes from increasing the strength of the electromagnets in the charging system. The engine braking effect is caused by drag from magnetic force.The car is being slowed  by powerful magnets!

Almost right, but the effect is due to putting a load on the motor, acting as a generator, converging mechanical energy into electrical energy via the effect of moving magnetic fields. Energy transfer.

It's just running the main motor with the power flow reversed, so will cause no more mechanical wear than when running the motor forwards. The other motor is directly connected to the ICE and is mostly run in this generator mode (after starting the engine).

There will be some losses to heat due to inefficiencies, of course. When the energy can't be dumped into the battery any more, conventional engine braking is used.

Something similar happens when you press the brake pedal, until the amount of braking force needed requires the use of the real brakes (or something like ABS is needed).