FlatSix911
Porsche 918 Hybrid
Great comparison ...
From the perspective of BMW, as is the case with most traditional automobile manufacturers (see Toyota's Mirai), the i3 BEV/i3 REX was an attempt to game the system by taking advantage of specific provisions of CARB regulations that provide extra-special ZEV Credit benefits to specific configurations of compliance cars. The idea was to combat the plug-in hybrid designs typically offered (and widely complained about by EV enthusiasts) that offer hundreds of miles of range on gasoline, but very few (9, 11, 13, 14, 20, 30 miles) on electric drive by setting up an incentive to build something that had a total range 51% electric and 49% ICE (or at least, close to those numbers). So, the i3 REX ended up with a teaspoon full of gasoline capacity to come just short of the maximum range the car could attain with electricity alone...
EPA Comparison: BMW i3 BEV, BMW i3 REX, BMW 330e, and Ford Fusion Energi