It spent just two or three lines for each car, and that was it. No mention to the Solterra – Subaru’s badge-engineered version of the Toyota bZ4X – but a new concept car will attract much more attention for putting STI in “a carbon-neutral era.”
This is the most revealing point of Subaru’s description of the STI E-RA Concept. It can only mean that it has electric motors and no combustion engine. A more remote hypothesis is that Subaru is also following Toyota’s idea of using a combustion engine to burn hydrogen, which is a lousy idea for multiple reasons.
Burning anything in a reciprocating engine will demand oil to lubricate the moving parts. This oil will eventually be burned as well, generating carbon emissions. T&E recently showed how synthetic or renewable fuels could only claim to be carbon neutral and nothing more. All the other pollutants generated by the combustion process will still be produced, some in a higher quantity than with fossil fuels. The nasty list presents nitrogen oxides, hydrocarbons, ammonia, and particulates. We’re sure a hydrogen-burning engine could generate NOx (combined with the Nitrogen from the air) and ozone.
However, the worst part of burning hydrogen is that it has a very low energy density per volume. While gasoline offers 34.6 MJ/L, liquid hydrogen delivers 10.1 MJ/L. It is worth remembering that liquid hydrogen has the best energy density per volume that the gas can offer, but it also has to be kept at under -252.87°C (-423.17°F).
Summing up, STI’s best shot would be to use fuel cells or a battery to achieve the carbon-neutral era that is STI E-RA’s goal. If it chose a battery pack instead of hydrogen, it could also try swappable batteries. After all, it is a concept car with motorsports roots. Acquiring “experience and practice in new technologies in the world of motorsport” requires experimenting.
The fact is that Subaru has already made its choices and will only reveal them at the 2022 Tokyo Auto Salon, starting on January 14. Hopefully, it will make its STI predecessors proud in a carbon-neutral era.