> Synthetic hydrocarbons and alcohols don't contribute to climate change at all.
If you are able to manufacture them in a completely emissionless way. That requires huge energy input though. Certainly has its uses, but too expensive for personal cars I'd think.
What I think would make sense is to use methanol as a seasonal energy store in temperate climates. Manufacture from PV in summer, burn in winter.
Methanol is the obvious choice, because there are so many ways to make it. Shipping certainly looks to be moving in that direction, though ammonia is also being trialled. Ethanol via fermentation is also doable at scale, but most effective pathways rely on using arable land.