Absolute speculation but a little research on the possible engine and drive train for an imagined CX PlusFour comes up with the B48 BMW engine used in the BMW 2 Series Coupe 230i. It is available with a 6-speed Getrag manual or an 8-speed ZF automatic.
The B48 used is a 2.0 L I4 turbo with 185 kW (248 hp) at 5,200 rpm and torque of 350 N⋅m (258 lb⋅ft) at 1,450–4,800 rpm.
CO2 emissions are 135 g/km, a vast improvement over the current Plus 4 and could even be less for the Morgan which would be lighter than the BMW.
Perhaps a more likely alternative would be the engine used in the 220i: a 135 kW (181 hp) version that develops more than adequate torque for a Plus 4 CX platform alternative: 290 N⋅m (214 lb⋅ft) at 1,250–4,500 rpm.
The way that tax is being levied on the basis of CO2 emmisions this might bring the on-road cost of a possible CX PlusFour to the same or less that a GDI Plus 4 in the same way that it has made the on-road cost of a PlusSix in some countries less than the cost of a conventionally aspirated V6 Roadster.
I will be very curious to see what, if anything, Morgan have in the pipeline. I feel that there must be both a 4 and a 3 cylinder version under consideration.
The BMW 218i produces 100 kW (134 hp) at 4,500–6,000 rpm and 220 N⋅m (162 lb⋅ft) at 1,250 rpm. CO2 emmisions are a mere 133 gm/km in the BMW and could well be less in a lighter Morgan. When it comes to performance in the real world torque is what it is all about and this would give brilliant performance for an entry point CX Morgan. A PlusThree?