Your second engine choice is the world's first production - ready variable compression ratio engine. (bestride.com)
Why will a lower compression ratio engine push the compression gauge to a higher number than a high performance, high compression engine? (mechanics.stackexchange.com)
Not only will this reduce the use of fossil fuels, but the higher purity fuels made in this way can be used in even higher compression ratio engines, increasing efficiency even more. (automobilemag.com)