The four banger mentioned above was the world's fastest vehicle at one time. (Faster than the then current airspeed record. )
They didn't have the technology at that time to make an engine more powerful by other means, so they made it BIGGER. Displacement, then, was how you made more power.
Post ww1, after technology had made leaps and bounds, a much smaller engine became the land speed record holder..... for about ten minutes. Till a huge, inefficient, airplane engined car cruised past the record, with out having to have huge rpm.