Of course they may just decide to not build a 4/4. Price wise using the CX platform...which is too wide for narrow wings...would mean even a three pot 1.5 would still be pretty expensive and would there be a market for a small engined car at that price level?
I think it is a big mistake to concentrate on the power output of the engines. The real consideration should be the the torque characteristics of the engine. I am not familiar with the BMW 3 cylinder engine but in general terms the small turbo charged engines have little torque at low revs and then come on strong as the turbo starts to take effect. Imagine the situation where you are negotiating a series of hairpin bends where with say a Plus 4 you would drop back to second gear; with a car that has a 1500 cc turbo engine you will find little power to accelerate out of the bend until the rpm rises to the torque band. Dropping back to first gear would be possible but then you would be revving the nuts off the thing and have to change up almost immediately. Fine if you are going for a hill climb record but hardly relaxed touring.
I am not really in the market for a new Morgan but I doubt I would consider the new PlusFour. To my mind around 185 hp and good torque from low rpm is more than adequate for a lightweight car.
I have the 1500 BMW 3 cylinder in the Mini and it a smooth torquey engine with a 6 cylinder soundtrack. It would be great in a light sports car but perhaps lost in the c.f. chassis
