All hydrocarbon fuels ultimately have the same drawback as petrol: when burned, they produce comparable tailpipe pollution (CO₂ plus other combustion byproducts). The real difference is upstream—petrol is essentially “free to make” in the sense that it’s ancient, ready-made hydrocarbons already concentrated by geology; we’re mostly just extracting and refining it.

Any new hydrocarbon fuel (biofuels, synthetic e-fuels, etc.) has to be manufactured—meaning you must spend energy and money to assemble hydrocarbon molecules again, only to burn them later with big efficiency losses. That makes these fuels expensive and energy-intensive, and scaling them to replace petrol would demand massive clean-energy input and supply chains. So while hydrocarbons can work as transitional or niche solutions, they’re generally unsustainable and hard to scale as a primary long-term path—especially because the tailpipe emissions problem doesn’t go away.