I meant it in the most literal sense possible. The density of liquid hydrogen is around 70kg/m^3, but the density of gasoline is around 700kg/m^3. This means th

I meant it in the most literal sense possible. The density of liquid hydrogen is around 70kg/m^3, but the density of gasoline is around 700kg/m^3. This means the despite all the carbon atoms, there are still more hydrogen atoms in a bucket of gas than in a bucket of liquid hydrogen. You are correct in that liquid hydrogen has more energy per weight than gas, but gas is ten times denser, so it has around three times more energy per volume, and both are important when it comes to designing a safe fuel container that fits in a car.