Back to the original question (differences between HPDI, Optimax and Etec), I would add that HPDI and Optimax have a mechanical "
single point of failure" (Optimax - air pump; HPDI - high pressure fuel pump). The Etec uses a "time proven" electric pump (similar to what has been used in the automotive world for 30 years as well as used in the marine 4 stroke world since they went EFI). Even if ...