To all designers, engineers and even just tinkerers who think about Sterling engines:
1. Could one build an engine that bears a magnet plunging into and out of an electricity generating coil just in a linear oscillating motion? Conversion to a rotary motion, with flywheels and cankshafts etc., could be bypassed. Of course, the frequency of this oscillation should be rather high - maybe 50Hz or 60Hz or even higher yet.
2. One point to gain or loose overall efficiency is the transfer of heat from the heat source - presumably a fire of sorts - to the engine. How would the burning chamber, as it were, and the heat exchanger optimized?
3. Does it make sense to heat up the driving gas in an extra chamber -separated from the engine proper, i.e. from the pistons and cylinders? Same for cooled down air. Yes, this might complicate the mechanism but it might improve drastically the efficiency and the dynamic behavior of the overall set-up.
These questions pertain to all sterling engines but are particularly important in an engine that drives a car, I suppose.