[Phantom]

I have thought about doing something similar to my Golf TDI but I would only have the electric motor running below 1800-2000 RPM. Something like the alt pulley on VWs would be good to disconnect the motor from the engine. The pulley allows the alt to free spin if it is moving faster than the motor reduces stress when I take 1st to 5500RPM and then shift to 5th at 950RPM or any spirited shifting.

If that pulley could be used on the engine side I could spin the motor up and the engine would take over after a set cut off speed. Down side no regen possible.

As for using an electric clutch like on an AC or PTO it should not be to hard to eliminate the harsh kick in. Using a motor controller it would need to be programmed to match speed with in a set percent when that is met it would send voltage to a relay that will give power to the clutch. The other part of the program that would have to be met would be the calculated load of the engine that should not be exceeded.

So if the engine currently runs like the following.
Load >80% V8
<80%V4

You would have the controller set up like the following.
IF Speed >50mph
and Load >75%
Regulate motor to engine RPM is with in 95-100%
Then Engage clutch.

After that you would just have the motor regulate speed based on the engine load and speed. Say have it turn off if <45mph, Load >92%, engine rpm <1500, and battery voltage is less than X.