With it being a small engine and micro cars - old or modern - usually use small engines, I think it would be a great way to power a small car. With older micro cars (Microcar.org has a list of older micro cars), they usually use one or two cylinder engines and this could - possibly - be used in them. Since it is scalable, one could use them newer or modern micro cars. I could even see it being used in small kit cars (there are plans at R.Q.Riley and other places).
I think this little engine could be used for more than just cars. Their web site shows it being used in a variety of ways. This is for another blog, perhaps one on how the little rotary engine could be used.
I worked on it and it is better.
it is at Cafe Press