There are only a handful of HP cars that are allowed the hybrid Level 1/Level 2 prep.
Not sure about the other E and F prod...
These are identified by going to the PCS section of the GCR and looking up the individual spec lines for each car.
In the first column labeled 'Prep Level' it will be listed one of three ways...
"Level 1" i.e. Full Prep
"Level 2" i.e. Limited Prep
"Level 1/Level 2 See Notes" i.e. Full Prep suspension, Limited Prep Engine/Drive Train
In HP, I think only the BMC Minis, Spridgets, Fiats, and Spitfires have this option.
Shoot a PM to Bartell for more info as I am pretty sure his car is a hybrid 1/2 prep level.