What does make a car engine technically a six pack?

Which is the better engine configuration for a fuel-efficient car?

• THIS? The Crower 6 cycle engine invented by Bruce Crower, the same guy who owns the popular aftermarket automotive camshaft company. Similar to a 4 cycle engine. Adds a 5th and 6th cycle where water is injected into the engine between the exhaust cycle and intake cycle. The water entering the hot combustion chamber instantly turns into steam and expands to 1600 times its volume giving an extra free steam driven power stroke. He claims a 40% reduction in fuel consumption and less emissions. In the prototype models the engine consumes about the same amount of water as fuel. However in production models the steam could be captured and condensed to be used repeatedly. An added benefit of this design is that it draws enough heat from the engine making the cooling system obsolete. http://www.damninteresting.com/the-six-s%E2%80%A6 OR THIS? A fully electric driven car with an auxiliary engine to charge the battery pack. The small auxiliary engine would only run when the car trip is expected to exceed the car's range. On short trips, it would be charged by house current. On longer trips a hybrid internal combustion(IC)/Steam engine would charge the battery. The IC/Steam engine would weigh under 150 lbs and only be used to charge battery pack. It would consist of a 2 cylinder gasoline engine combined on the same crankshaft with a Steam engine that would run off the exhaust heat from the IC engine. Like the Crowler engine, there would be no need for a cooling system as all the waste heat would be used to power the steam engine.

• Answer:

  The problem with the 2nd design would be the ability to charge the batteries quickly enough to continue driving the car over longer distances. Chevy's new Volt hybrid is going to use a very similar setup to your 2nd design - a gas engine charging batteries while an electric motor draws power from the batteries to actually move the car down the road. The thing is, the Volt has a 140(ish) horsepower 4-cyl gas engine to charge the batteries over long distances. If Chevy could have used a smaller, lighter, more efficient engine to do the job of recharging batteries once the initial charge was depleted, I can assure you they would have. They used a larger, heavier engine than you propose because they had to. As for powering a steam engine from exhaust heat, you'd get very minimal power for the added weight and complexity of adding the steam engine - to the point it wouldn't be worth doing, especially on a small 2cyl engine. If it were possible to extract useful power/efficiency from powering a steam engine from exhaust heat, I can assure you car manufacturers would already be doing it. They aren't. I'd go with choice A of the 2 choices, but your choice B in the refined form of a Chevy Volt is probably more efficient (and likely more practical with existing technology) than either of the choices IMO.