Hey Scotty, here's a question that spans Honda motorcycles & Honda cars. For many years Honda has been designing and building initially 4 cylinder then later 6 cylinder flat engines for their Gold Wing motorcycles. Do you know why Honda never developed this engine for a Honda Civic or CRV for instance?
Probably just cost more to build.
Different engine configurations (inline, V, W, flat) have different advantages and disadvantages. For flat/boxer engines, the primary advantage is lower center of gravity. Porsche uses that configuration to improve handling, and Subaru does it to allow more ground clearance. But the disadvantages include a small amount of increased complexity and more difficult service access.
Developing a motor is a huge investment, and generally even a company as big as Honda isn’t going to waste time on a motor unless they really need it. Occasionally they might make a niche motor for a very special car (S2000) but boxer cars aren’t really Honda’s thing.
I would have loved to see one in the old CRX, though.
If I were to guess, it’s because the lineage of the Civic and CRV didn’t lend itself to its development.
My guess is that a cycle engine doesn't develop enough torque to move a car
