1910 Stanley Model 85

1910 Stanley Model 85 is a two-cylinder steam car rated at 30 horsepower. It has a water capacity of 100 gallons, achieved through plumbing together three separate tanks. 

The Stanley engine produces four power strokes per revolution of the crank shaft, which translates to more power with every stroke. There is no clutch and there is no transmission, but the gear on the steam engine crankshaft is directly engaged with the ring gear of the differential. A transmission isn't needed because the engine stops when the car stops, similar to a steam locomotive.

A steam car has more power per pound than an equivalent internal combustion engine. With a steam engine, steam is emitted for 80% of the stroke, providing more uniform power for a longer duration of the stroke. This, along with the continuous push of the piston, provides an advantage of more torque in a smaller package.