It's a $5 Trillion dollar company.
This, and the 'male contraceptive with no side-effects' are 'magic claims' style companies, where if their claims are true, they immediately massive companies.
Usually, the devil is in the details. A few little things here and there contextualize the claims.
Think of how many smart people we have working on big problems and how few real breakthroughs we have.
These things will mostly be evolutionary. Like 'male contraceptive' but it actually does have the side effect of long-term problems. Or takes a year to wear off. Or is $20 a pop and last for 1 hour. Or is only 95% effective. Etc. etc..
So my complete seat-of-the-pants, duffer-on-the-bench guess is that they have a CO2 capture process (or use CO2 from a nearby industrial combustion process), use the CO2 in their process to separate gasoline in place of a traditional distillation process, then remove the CO2 from the gasoline by precipitating it as ammonium carbonate, which can be sequestered somehow.
Does the $3/gallon include both?