Real world ICE drive train losses.
http://www.fueleconomy.gov/FEG/atv.shtml
They look a bit dodgy but a lot closer than the ones you stated.
Your own motor references showed motors over 95%, complete genset "Overall efficiency of a Polar DC genset is between 75 and 85%"
And for the average user in a series hybrid the ICE will rarely be used as it is range extending only.
This was a few minutes searching not the best out there.
Just found this for the Prius