vocabulary can make one sound smart.  The combustion engine has been around for a long time and is long past due for a change, oh but wait there were cars back in the 60's that got 50-80 mpg.  It's now the year 2008 and what progress has been made?  jack shit.  All the hype is about this hybrid bullshit.  "oh look now the Chevy Tahoe gets 22 mpg" or whatever that oversized hybrid gets.  They just do that shit to make it seem like they're really trying or that they really care.  If they really did want to make a difference, one simple way to change their engines is to simply toss out the over head valve design and go with a dual overhead cam, like honda has been doing for a loooooong ass time.  right there you will get 2 hp per cubic inch versus 1.  I honestly know don't that much about cars but that's a proven fact right there.  The car companies want to suck as much money as possible out of the Internal reciprocating combustion engine because that's what they've been making for years and already have the machinery to build them and anytime that someone makes a new design that will blow away the competition, they do almsot anything possible to push them out of the market, or buy their ideas.  Who do you think has a lot of money invested in oil?  car companies.   Ever see the movie "Tucker?"
It's all about power and money, not about figuring out how to do things differently, cuz i can almost guarantee that theses companies and other companies have had enough money to research and test other means of fuel and or power for quite some time now, their just isn't any profit in it, YET.
We didn't implement the metric system cuz we're lazy ass americans that don't wanna spend the coin and think we're better than everyone else.  It's really not that costly, just start teaching kids in schools right now.  We've just got our ego's to fight with.
How is hydrogen made?  Think we're gonna run out anytime soon?