can a car run on water

[McReese]

No, a standard gasoline or diesel car cannot run on water as a fuel source. The idea of a "water-powered car" is a persistent myth, often confused with technologies like hydrogen fuel cells. While water contains hydrogen, the energy required to split the H₂O molecules through a process called electrolysis is greater than the energy you can get back by burning the hydrogen. Using your car's electrical system for this would drain the battery inefficiently. True water-to-energy combustion is not scientifically viable with current technology.

However, the concept often stems from real, albeit misunderstood, technology. Hydrogen fuel cell vehicles (FCEVs), such as the Toyota Mirai or Hyundai Nexo, use hydrogen as fuel. This hydrogen is stored in high-pressure tanks and combined with oxygen from the air in the fuel cell to create electricity, which powers the motor. The only emission from the tailpipe is water vapor. The key distinction is that these cars run on stored hydrogen, not water itself. The hydrogen must be produced elsewhere, often from natural gas or via electrolysis powered by renewable energy.

The main challenges are infrastructure and energy efficiency. The "well-to-wheel" efficiency of a hydrogen FCEV is generally lower than that of a Battery Electric Vehicle (BEV) due to energy losses in production, compression, and transportation. For most consumers, BEVs represent a more accessible and efficient zero-emission solution today.

Technology	Fuel Source	How It Works	Tailpipe Emissions	Real-World Example
Standard Gasoline Car	Refined Crude Oil	Internal Combustion Engine	CO₂, NOx, Particulates	Toyota Camry, Ford F-150
Battery Electric Vehicle (BEV)	Electricity (Grid/Battery)	Electric Motor Powered by Batteries	Zero	Tesla Model 3, Ford Mustang Mach-E
Hydrogen Fuel Cell (FCEV)	Compressed Hydrogen Gas	Fuel Cell creates electricity from H₂ + O₂	Water Vapor	Toyota Mirai, Hyundai Nexo
Mythical "Water-Powered" Car	Water	Not Scientifically Viable	N/A	None