In line electric motor in drive shaft?
 

So coming up with the idea that an in line electric motor may be able to be beneficial. My idea is to incorporate an electric motor on the driveshaft of a transverse engine layout with haldex awd.... regenerative braking to help with range would be all 4 wheels turning it.... is there a good choice of motor I could do this with? Just to help take the load off the engine a bit on acceleration?

I have only been aware of a similar project meant for longitudinal-engined RWD and 4WD.

Example? Two hub motors?

No I'm thinking a motor in the center of the driveshaft

On a vw with haldex, you could put an in line motor in to drive assist the front all the time and the rears when the haldex unit is engaged.

So we're talking about this?
https://blog.ecstuning.com/wp-conten...ex-800x400.jpg
https://blog.ecstuning.com/wp-conten...ex-800x400.jpg

Seems like rabbit hole.
innovationdiscoveries.space/the-haldex-all-wheel-drive-system-everything-you-need-to-know/

What are the dimensions of the driveshaft? What structure does it pass through? With no universal joints, might any solution generalize to any (e.g.) front engine/rear transaxle vehicle?

Never seen anything that could relate to that.