With water – a more energy dense fuel. We use it to do Nuclear Fusion.
Burning diesel/petrol already does Molecular Nuclear Fusion
The burnt fuel sets up a steam plasma – which does Molecular Nuclear Fusion r(He2++O++3e-+E3+L+X-ray). So we would rather not oxidise the C atom.
In the 1950s, steam barges on Windscale set up a Windscale kettle. This bubbled steam through water, and boiled a kettle in 10 seconds.
2 H2Os+H2O->He+O+H2O+E2+L+X-ray doing Molecular Nuclear Fusion in the 1950s.
Why did nobody tell me on my M. Eng in 1982? They already knew a steam engine gave off X-rays, massive heat and produced helium gas.
So to make a more powerful steam engine, introduce helical turbulence in the steam pipes – and more than double the power: idea mentioned on my PhD 2000. Great idea Dr Z!
So we take a present car, but introduce a 1L steam flask in the boot. We start off with liquid water, and lower the base ¼ of the way, and strike up a spike. Like street lights of old, we get a plasma burn.
So we use 1 spark every 5 minutes, to keep the steam hot. We encase the boiler in a coiled pipe, and thermal insulation.
We introduce the steam into the cylinder, and compress it. When we fire off the spark, we do 4. And get such a powerful down motion – so we need to draw in air – or the engine will destroy itself.
We take out the exhaust steam, along the tube coiled around the steam boiler – why waste the heat. This will keep the steam hot, with no spark. So once the engine is running, only the engine spark is required.
We take the exhaust steam to a major radiator on the roof – thermally insulated from the passenger compartment.
The steam condenses to water and air, We recycle the water – and expel the hot air. At 90oC. In cold countries, this is free hot air to warm the passengers.
So we drive the car, using a miniscule volume of regular water. Leakage from the steam system is massively more important. We are talking about 5x10-18cc of regular water a year.
So we recover most of the water. And drive a sports can, with no CO2, Fossil Fuels burn of battery use.
This is the sort of technology Ford, BMW and Nissan should be working on. So we keep all the present car engineering. A steam plasma tube driving a thermoelectric generator will produce 144kW of power. Enough to drive 18 houses.