However, one fundamental problem is that when you reduce the engine to the smallest possible size with these technologies, it's still a block of metal -- and a heavy one at that.  Some creative thinkers are looking to implement a dream they've had for over 25 years -- creating a mostly plastic engine.

Car engines are still typically made by pouring melted metal into molds -- a tweaked version of a 6,000 year old process.  Engineers like Matti Holtzberg, a New Jersey engineer who's been designing plastic engines since the 1980s, envision a very different production process -- one that uses molded plastics.

Mr. Holtzberg has paired with Huntsman Corporation of Houston, a global chemical company which employs 12,000 employees and rakes in $10B USD per year, to market plastic engines.  Currently, the average car has approximately 300 lbs of plastic -- typically including plastic interior paneling and exterior plastic bumpers.  However, the leading material, by weight, remains metal. Steel in the frame and iron or aluminum castings for the engine blocks and cylinder heads, transmission cases and axle housings are prevalent in modern cars.

It is the goal of Mr. Holtzberg to replace these metal engine and drive components with composite plastics, with metal protective metal casings in the areas exposed to the greatest heat.

Mr. Holtzberg's company is named Polimotor and it was first founded in 1979, a year in which it produced its first engine -- a Ford Pinto clone.  The engine used a plastic block, piston skirts, connecting rods, oil pan and most of the cylinder head.  The bore surfaces, piston crowns and combustion-chamber liners were iron or aluminum, and crankshaft and camshaft were metal.  Two years later the company was producing a 300 hp, 152 lb engine, which compared very favorably to a 88 hp, 415 lb standard engine.

During the 1980s the company continued to develop its idea and sold engines to racing firms.  However, it received little attention from the consumer market.  Undeterred, Mr. Holtzberg continued to work towards a mass-market plastic engine, experimenting with different types of plastic, such as phenolic resin.

Now they're trying to push the results onto the broader market.  They estimate that plastic components could reduce engine weight by 30 to 35 percent, save development time, and manufacturing costs.

Still, despite the backing of a major automotive chemical firm, many obstacles remain to the plastic engine.  Describes Richard A. Schultz, a consultant at Ducker Worldwide, "While half of the aluminum car wheels now come from China, the foundries supplying major aluminum powertrain castings are captive.  Energy consumption is not an issue, their aluminum scrap is readily recycled, and the cycle time with plastic would surely be longer."

Even if Mr. Holtzberg can sell the industry on plastic engines, there's still other challenges.  Plastics are generally produced from petroleum -- a fossil fuel.  Thus as fossil fuels become more scarce, plastics also are likely to become more expensive.  Plant-based plastics are being developed, but it may be difficult to tweak them to the same strength or stability as oil-based plastics.

Despite these major obstacles, Polimotor keeps chugging along.  So while it's no sure bet, don't be overly surprised if you see a plastic engine in your car, sometime in the future.