The term compliance vehicle is misunderstood by many, and in the broadest brush often refers to any EV not made by Tesla.
EV's are needed not to MPG requirements in California and other"CARB" states, but to garner ZEV (zero emission vehicle) credits.
Manufacturers are required to have credit equaling 9.5% of sales for 2020. It's a fairly complicated system, and different vehicles earn varying amounts of credits, so it doesn't mean that 9.5% of vehicles sold must be EV's.
PHEV's can count for only a portion of those credits (categorized as TZEV credits - the T is for Transitional).
If a manufacturer does not have the required number of credits for their sales volume, they can either "buy" them from the State for $5K per credit, or purchase them from manufacturers with excess credit at wahtever "market price" is. The first several quarter that Tesla showed a profit it was due to their sales of these credits.
A compliance car is sold in limited quantities and limited markets (CARB States or some subset) solely to earn credits. They are often sold or leased at a loss. The Clarity FCX and BEV are most definitely compliance vehicles. The PHEV cersion has been - at times - essentially restricted to CA, and would then fall in that category. When it was available nationally, it does not meet the original definition of compliance vehicle.